Why doesn't anything open in Yandex. Modified hosts file. Checking your browser settings

Such problems are not at all uncommon. Users quite often may encounter the fact that Yandex browser does not respond or does not open the necessary pages. There are a fairly large number of possible reasons, and this article discusses the most common of them.

The following settings may cause your browser to crash:

  • No internet connection.
  • Infecting a personal computer with viruses.
  • Hosts file
  • Problems with DNS.
  • Blocking of sites by the system administrator or firewall.
  • Technical problems with the site itself.
  • The system registry entry AppInit_DLLs is damaged.

This is a very broad and, at the same time, the most common reason why the Yandex browser takes a long time to load or does not open various sites at all. This may include:

  • Technical work in the server part of the provider.
  • Accident on the line.
  • Damage to your home cable.
  • System failure or router failure.
  • Your computer's network card is damaged.
  • Incorrectly installed network adapter drivers.

To diagnose this problem, users need to look at the network connection icon in the tray. If there is a yellow "!" - an exclamation point or a red "X" - a cross, which means that there really are problems with the network.

In this case, not only the Yandex browser will stop working, but also all other programs that require an Internet connection. Users in this case can try the following steps:

  • Inspect the patch cord coming from the router for physical damage.
  • Reboot the router to prevent it from freezing.
  • Restart your computer - in some cases this may help. For example, if a Windows service required for network operation has frozen.
  • Call the technical support service of your Internet provider and leave a request about the problems that have arisen.


Most likely, two such files will be stored on your personal computer - in the “HKEY_LOCAL_MACHINE” directory and in the “HKEY_CURRENT_USER” directory. The contents of both entries must be deleted.

Using the command line, users can try to solve two problems at once - clearing the DNS cache and clearing the list of static routes. Follow the few simple steps outlined in this step-by-step guide:


After these steps, you can close the console window and try opening a website again.

Hosts file

If none of the steps described above helped, and the Yandex browser still does not load Internet pages, you should pay attention to the “Hosts” system file and carefully study it. This text document contains the addresses of sites that the computer user cannot access. When you try to open such a website, the Yandex browser will redirect you to the “localhost” service page (or any other, depending on the settings).

Open the program for working with files and folders in Windows – Explorer. You can do this from the Start menu icon, from a desktop shortcut, or from the folder icon on the Quick Access toolbar.

Open the partition of the hard drive on which the operating system is installed. Go to the "Windows" directory. Here you need to find the “System32” directory. Go to the internal “Drivers” folder, and then to the “ect” directory. Here is the file you need called “hosts”. Open it using Notepad.

Several lines will be written here, starting with the hash symbol “#”. Find a line that looks like “127.0.0.1 localhost”. It should be located at the very end of the document and be the only entry without a “#” hash. If you find anything else in this file, delete it, after copying the entire contents of the document to a safe place just in case.

Infecting your computer with virus programs

Although trivial, viruses are the most common cause of all computer problems. If your Yandex browser suddenly begins to work poorly (slows down, is glitchy, does not load pages, displays various errors), its service files may have been damaged by viruses.

It is worth remembering that a computer with Internet access is very vulnerable to virus attacks, which can await the user on a huge number of sites. Therefore, such a PC must be protected with a special anti-virus program that quickly blocks malicious scripts from entering the hard drive, prohibits their execution, and also finds and destroys viruses already existing in the operating system.

If you do not have any anti-virus protection utility installed on your PC, it is strongly recommended that you download one, install it, and immediately run a full system scan. For example, you can use software from Microsoft called Security Essentials. It can be downloaded by following this link https://www.microsoft.com/ru-ru/download/details.aspx?id=5201.

Problems on the site itself

Finally, it is worth noting that if only one specific resource loads poorly in your Yandex browser, most likely there are no problems on your side. It is likely that the site is simply undergoing scheduled maintenance or equipment changes.

Was the article helpful?

Yandex browser continues to gain popularity. More and more people are installing it. With all its advantages, it does not do without some rough edges. Many of you have probably encountered a problem where your browser refuses to open a web page.

Problems of this kind are usually divided into two groups: those related to the browser itself and those not related to it. It’s very easy to check which option your case belongs to. To do this, open some other browser. In addition to the Yandex browser, this can be Opera, Safari, Google Chrome, Mozilla Firefox and Internet Explorer. If the desired link does not open there either, then the problem most likely has a direct connection with the connection to the network and the Internet.

Before starting any diagnostic work, make sure that the latest version of Yandex Browser is installed on your computer. You can simply download Yandex Browser and install it on top of the version that is already installed.

Problems with the site

It is immediately necessary to highlight one more type of problem. Therefore, before switching to other programs for viewing web pages, check how the Yandex browser behaves with several more sites. If he switches to other Internet resources, then the problem is most likely with a specific site. But we can’t say that definitely. Why? We'll find out below.

Antivirus problems

Most free antiviruses have the ability to add a site to the blacklist. So be sure to check the blacklist. Perhaps you weren't the one who added it there. If you give such rights, then antivirus programs can block access to those sites that they themselves consider unsafe.

Interesting fact: the opposite also happens, when access is blocked not by an antivirus, but by a virus. To find and remove it, perform a full scan of your computer.

Connection problems

Solutions to these problems are often standard: check the cable connection to the computer or router, check the router’s connection to the network, check the connection on the computer. If all of the above is normal, feel free to call your provider. It will tell you what other settings you can check. It is the provider's responsibility to determine what the problem is. It also happens that the reason may be a simple non-payment.

Problems with Yandex Browser

The most common problem of this kind is a system error. It is quite difficult to deal with it, so it is recommended to immediately carry out the processes of uninstalling and reinstalling Yandex Browser.

Another possible step is clearing cookies. This can be easily done through the Yandex Browser menu. Another option is to install a special program that will clear cookies on its own.

How to clear cookies in Yandex Browser yourself is shown in this screenshot in a video step-by-step diagram.

And finally, many people believe that ad blockers can block access to the site. Programs like Adguard primarily deal with eliminating advertisements. However, if the site is one continuous advertisement, then it may be that nothing will be displayed. But in such a case, this site will definitely not be useful, so the ad blocker here should only say “thank you very much.”

Browsers are software designed specifically to allow users to surf the Internet. But sometimes such programs can fail. Next, we will try to find out why Yandex does not load. What can be done to restore the functionality of the application in question? The simplest instructions will help you understand the task. Even a novice PC user can solve the problem. Sometimes this takes about a few minutes.

System failure

Why won't Yandex load? The first scenario is that a failure occurs in the OS. Anything can trigger it.

The situation is very easy to fix. The user just needs to restart the browser. Even better is to restart the PC. Then the software will work fine.

Important: in case of critical system errors, immediately after restarting the PC, automatic correction will begin.

System hangs

Yandex.Browser won't load? There are various reasons for this browser behavior. Sometimes it is caused by the OS freezing. Typically, owners of not very powerful computers encounter such problems.

When the operating system freezes, any user actions in the OS are ignored. Rebooting the computer helps correct the situation.

CPU overload

Why won't Yandex load? In some cases, users are faced with severe OS overload. This causes applications to freeze and Windows to run slowly.

If the user suspects processor overload, it is recommended:

  • close a number of optional and unnecessary programs (especially those running in the background);
  • turn off the antivirus;
  • disable all “serious” programs (those that take up a lot of PC resources).

Only then can you resume attempting to use the browser. Usually, the functionality of the corresponding application is restored when the PC processor is unloaded.

Viruses in the system

Yandex home page won't load? Are the browsers on your computer slow or not working? Are some sites unavailable for viewing?

Sometimes a similar scenario occurs when the operating system is infected with viruses or computer spies. The situation is corrected in a few minutes.

The user will need:

  1. Conduct a full scan of the operating system for viruses and computer spyware.
  2. Treat all potentially dangerous objects. Anything that cannot be treated should be removed.
  3. To restart a computer.

Typically, such instructions help get rid of viruses. The operating system starts to work normally. And all pages in the browser will open without much difficulty.

Important: to check your PC for spies, you can use the SpyHunter 4 application.

Cleaning the hosts file

The Yandex home page and other sites may not open due to changes in Windows system files. This situation usually occurs when a PC is infected with a virus.

The following instructions will help you get your browser working:

  1. Go to C:/Windows/System32/drivers/etc.
  2. Open the hosts file using the Notepad service.
  3. Erase everything that was written in the corresponding document.
  4. Save changes.

Now you can restart the operating system and try again to work with the browser and previously disabled sites.

Software updates

Yandex won't load? What to do? The algorithm of actions will directly depend on the cause of the failure.

The browser may not start due to automatic downloads of updates. When the initialization of the new software version is completed, the software will operate as normal.

Typically, users are prompted to download browser updates automatically. If you wish, you can disable auto-update in your Internet browser settings, but this is not recommended.

Outdated programs

How to open Yandex.Browser if it does not start? The reason may be that you have an old version of the software on your computer.

The thing is that program creators from time to time stop supporting their old software builds. This causes previously installed utilities to stop working.

If a person has not updated his Internet browser for a long time, he is recommended to:

  1. Launch any browser after first connecting to the Internet.
  2. Open the Yandex website.
  3. Find and download the latest version of Yandex Browser.
  4. Run the installation file. Before this, you will have to uninstall ("Start" - "Control Panel" - "Uninstall Programs") the old version of Yandex and close the active Internet browser.
  5. Complete the process following the instructions of the installation wizard.

That's all. You can immediately start working with the updated Internet browser. It is advisable to reboot the OS after initializing the corresponding software.

Installation errors

Yandex may not start due to incorrect software updates or initialization errors. There is no way to insure against such situations. They can occur completely randomly.

What to do? browser occurs after the corresponding program is completely uninstalled and reinstalled. Sometimes the procedure has to be repeated several times.

Antiviruses - evil or protection

Why won't Yandex load? In some cases, a similar problem occurs due to antivirus software.

The thing is that operating system protection software sometimes blocks Internet browsers. To correct the situation, just disable the antivirus. For example, for a few minutes. After starting the browser, you can resume the antivirus.

Important: some antivirus programs allow you to add software to exceptions. The corresponding menu item is located in the "Settings" section. It allows you to unlock locked programs and utilities.

Running processes

Why won't Yandex load? It happens that programs start in More precisely, their processes appear in the task manager, but no changes are observed on the screen.

To launch an application, you will have to end all “background” processes of the selected utility. In our case, this is Yandex.

The algorithm of actions will be as follows:

  1. Press Ctrl + Alt + Del.
  2. Select the "Task Manager" menu item.
  3. Open the "Processes" tab.
  4. Select all lines responsible for the operation of Yandex.
  5. Click on the "Finish" button.

Next, you have to agree with the irreversibility of the procedure and familiarize yourself with information about the likelihood of errors in the operation of the OS. It is done. Unnecessary processes are disabled. Now you can just launch your browser and wait a bit.

Overclocking the system

Why doesn't Yandex start? Browsers load very slowly when overclocking the operating system. This is the name given to the process of fully loading Windows after rebooting or turning on the PC.

Once the desktop appears on the display, the user needs to wait. 1-2 minutes is enough. During this time, the operating system will boot.

If the user was in a hurry and immediately clicked on the “Yandex.Browser” icon, he will have to wait until the OS is overclocked. Immediately after this, the Internet browser will start and work normally.

Problems on the site

Yandex mail won't load? Previously, we looked at the causes of problems with Internet browsers. Why do some pages not load from time to time?

Yandex (and any other Internet resource) may not work:

  • if they tried to hack it;
  • in case of problems with the Internet connection;
  • if there are too many tabs open in the browser;
  • under heavy load on the PC processor;
  • if the operating system is infected with viruses or spyware;
  • during technical work;
  • when there is a heavy load on a particular service (occurs during rush hour).

As practice shows, it is enough to wait a little and then resume attempts to work with the site. If waiting does not produce any results, you will have to check your computer for viruses and edit the hosts file.

If all else fails

Unfortunately, the tips and instructions listed do not always help. Users sometimes complain that Yandex never launched. What to do in such circumstances?

We'll have to take drastic measures. We are talking about reinstalling the OS. To do this you need:

  1. Insert the installation disk or flash drive into the PC.
  2. Launch the installation wizard.
  3. Follow the instructions on the screen.
  4. It is advisable to completely format the hard drive. Then all OS problems will be fixed.

Once the operating system boots, you can install the browser and network card drivers. After this, all programs and sites should work properly.

Some users may experience that their Yandex browser takes a very long time to open or does not work at all. If this web browser is your main one, then this can seriously interfere with your Internet browsing. The article describes why such problems may occur, as well as what to do if they occur on your personal computer.

There are many reasons why the Yandex browser may freeze and take a long time to turn on. This article discusses the most popular problems that users can resolve on their own:

  • Windows system services freeze.
  • Incorrect browser installation.
  • Infection of a personal computer with malicious scripts.
  • Damage or deletion of program service files.
  • Heavy load on the computer's computing resources.
  • Damage to the operating system.

System hangs

One of the most common reasons why a certain program does not work correctly is the freezing of one or more Windows services. This does not necessarily mean that Windows needs to be reinstalled, most likely it just needs to be restarted.

Restarting the OS often helps resolve a fairly large number of problematic situations, so it is recommended to do it first. In order to restart your personal computer, you need to launch the “Start” menu, click on the right arrow icon next to the “Shut down” button, and select the “Restart” option from the drop-down list that opens.

If after this operation the problem remains and the Yandex browser still does not work, you need to do the following methods.

Uninstalling an old version of the program

The Yandex browser constantly creates new files, downloads additional updates, changing its structure. If for some reason a system failure occurs during such processes, the browser's service files may be damaged, as a result of which it may stop launching.

Another reason why this happens is that files are damaged by dangerous viruses and then cleaned by an antivirus program. After such operations, some information may be lost, which will lead to problems when attempting to start. Finally, some users may delete some important files themselves due to negligence.

In this case, you need to completely reinstall your Yandex browser. To do this you need to do the following:


Reinstalling the browser

After you successfully remove the damaged version of the program, you need to download and install the new one. Follow the link https://browser.yandex.ru/new/desktop/custo/main/?_rdr=safe (this can be done from any other browser, for example, Internet Explorer) and click on the “Download” button.

Run the saved exe file to begin the browser installation process. The time for this procedure depends on your Internet speed and computer performance.

Antivirus protection

A common reason why some programs cannot be launched is that the personal computer is infected with viruses. When working on the Internet, users will certainly encounter a huge number of malicious scripts.

To protect against dangerous programs, specialized applications called antiviruses are used. The antivirus not only protects your system from infection in real time, blocking the execution of harmful scripts and the downloading of viruses, but also regularly scans all files stored on your hard drive.

If one of them is infected, the program will try to clean it. If unsuccessful, the file can be deleted with the user's permission. It is recommended to do such checks at least once a week. Such precautions will allow you to protect your personal information and installed programs from damage.

If you do not have any antivirus installed on your computer, it is highly recommended that you select one and download it. For example, users can take advantage of Microsoft's antivirus protection tool, Security Essentials. This program is free and is freely available for download at

Currently, the Yandex.Browser web browser has gained enormous popularity among the segment of Russian-speaking Internet users. It is characterized by stable operation, a high level of protection against malware and the presence of a turbo mode that doubles the performance. However, in some cases, for one reason or another, the browser stops starting and loading sites. To eliminate this problem, it is necessary to use proven methods that are widely used in the user environment.

Why Yandex.Browser does not start

Yandex.Browser rarely starts to malfunction. If this happens, the problem may be caused by user errors or incorrect software operation.

The following may cause the browser to be unable to launch:

  • a browser conflict with one of the applications installed by the user over the last period of time;
  • incorrect update of Windows files made from the manufacturer’s website;
  • incorrect update of Yandex.Browser made from the developer’s website;
  • blocking the browser with a new antivirus program;
  • blocking the browser by the system firewall;
  • lack of RAM and cache memory load;
  • Hard drive failure due to unexpected computer shutdown;
  • using special utilities to correct system errors downloaded from an unverified site;
  • launching a large number of applications.

To resolve these problems, you must successively apply the methods described below.

Reboot "Yandex.Browser"

  • the web browser stops loading web pages;
  • The browser automatically unloads open web pages that are not yet finished working with.

To properly restart Yandex.Browser, you must complete the following steps:

  1. Launch Yandex Browser. Double-click on the icon on the “Desktop” or single-click on the browser icon on the “Taskbar”.

    Double-click on the icon on the “Desktop”

  2. Type the command browser://flags/#max-tiles-for-interest-area or simply browser://flags/ in the search bar.

    To view installed flags, type browser://flags/

  3. In the window that opens, find the lines “Offline Auto-Reload Mode” and “Only Auto-Reload Visible Tabs”.

    Find the flags you want to disable in the list

  4. In the drop-down menus on the right, replace the lines “Default” with “Disabled”.
  5. Restart Yandex.Browser by clicking on the “X” icon in the upper right corner and launching the web browser again.

    Click on the "X" icon in the upper right corner of the program

If after restarting the browser its functionality is not restored, then you need to restart your computer.

Video: how to properly restart Yandex.Browser

Rebooting your computer or laptop

A hard reset can be performed in several ways:

  • press the Reset button located on the computer system unit to reboot;

    To restart your computer, press the Reset key

  • press and hold the power button on the system unit or laptop until the computer turns off, and then after 5–10 seconds turn on the computer;

    To turn off the power, press and hold the key until the computer turns off

  • press the Ctrl + Alt + Delete keys, in the window that appears, click on the power off icon at the bottom right and in the drop-down menu click on the “Restart” line;

    To reboot, press the Ctrl + Alt + Delete keys, click on the power off icon and select the “Reboot” line from the drop-down menu

  • apply the standard reboot method using system tools.

The standard way to restart a computer or laptop is using the system software. To do this you need to follow these steps:


Video: how to restart a computer or laptop

Terminating unnecessary processes in Task Manager

To avoid having to restart your computer and avoid losing unsaved information, you can end all unnecessary processes in the Task Manager and free up RAM:

  1. Hold Ctrl + Alt and press the Delete key.

    Hold Ctrl + Alt and press the Delete key

  2. In the window that opens, click on the “Task Manager” line.

    In the window that opens, select “Task Manager”

  3. Select the Processes tab from the menu.
  4. Select an unnecessary application or background process by highlighting it and click on the “End task” button.

    To end an application or background process, select it and click on the “End task” button

  5. Go to the “Details” tab, select the processes associated with yandex.exe, and clear the tasks.

    Go to the “Details” tab and clear tasks associated with “Yandex.Browser”

Video: how to kill unnecessary processes in Task Manager

Yandex.Browser update

There are two ways to update Yandex Browser. One of them is performed in manual mode, and the other in automatic mode.

Manual update

Manual updating can be performed from any search engine:

  1. Type “Yandex” in the search bar or click on the icon of the same name in the browser.

    To launch the search engine, click on the “Yandex” icon

  2. In the search engine window, click on the Yandex.Browser logo.

    To start installing and updating Yandex.Browser, click on its logo

  3. Open the downloaded file.

    To start the update, click on the downloaded file

  4. In the panel that opens, remove or leave the checkbox that determines the installation of Yandex.Browser as the default web browser.
  5. Click on the “Install” button to install and update Yandex Browser.

    Click on the “Install” button

Video: how to manually update Yandex.Browser

Automatic update

Yandex Browser is automatically updated regardless of whether the web browser is running or not. The process is carried out directly in the browser. To start the update, you must follow the following step-by-step instructions:

  1. Launch “Yandex.Browser” by clicking on the icon on the “Desktop” or on the icon in the “Taskbar”.

    To launch Yandex.Browser, click on the icon on the “Desktop” or on the icon in the “Taskbar”

  2. In the upper right corner of the browser, click on the “Yandex Browser Settings” icon, which is three horizontal lines.

    Click on the “Yandex Browser Settings” icon

  3. In the drop-down menu, move the pointer to the “Advanced” line and select “About Browser” from the drop-down menu.

    In the drop-down menu, select “About Browser”

  4. The browser will automatically update in the panel that opens. If the update is not required, it will be indicated: “You are using the current version of Yandex.Browser.”

    If necessary, the browser will automatically update

Video: how to automatically update Yandex.Browser

Removing the old version and installing Yandex.Browser

Uninstalling the old version and installing a new one will help correct serious errors in the browser.

Uninstalling Yandex.Browser

Complete uninstallation of Yandex.Browser may be necessary if the error that occurs when launching the application is so serious that it cannot be eliminated.

There are two ways to uninstall the browser:

  • using the uninstallation utility built into the system;
  • using a third party program.

To remove Yandex Browser using the uninstallation utility, you must follow the following step-by-step instructions:

The algorithm by which the built-in utility performs the removal does not work entirely correctly and leaves “tails” of the program being removed. For example, when you uninstall Yandex Browser, lines remain in the system registry, and the Yandex directory remains in the Program Files and ProgramData folders. This can lead to the fact that when installing a new version of the browser, files will be placed in faulty directories, and faulty lines in the system registry will not be replaced. Thus, the new version will still work with errors.

To avoid this problem, to uninstall Yandex Browser, I recommend using a third-party program, for example, Your Uninstaller PRO. It is not tied to system processes and works offline, which allows you to completely remove the browser, all its settings and traces. The program does not take up much space on your hard drive and is unpretentious to RAM resources. In personal testing, it showed better results than the famous uninstaller Revo Uninstaller.

You can uninstall the program using Your Uninstaller by following the step-by-step instructions:

  1. Launch the Your Uninstaller program by double-clicking on the icon on the “Desktop”.

    Double-click the Your Uninstaller icon

  2. In the program console, select Yandex in the list of programs.

    In the program console, select the “Yandex.Browser” icon

  3. Click on the “1-click delete” button at the bottom of the console.

    Click on the button “Delete in 1 click”

  4. Preparations for uninstalling the program will begin, checking the registry and installation folders associated with Yandex.Browser.

    Preparations are underway to remove Yandex.Browser

  5. After preparation, deleting entries from the registry will begin.

    Wait for the process of deleting entries from the registry to complete

  6. In the final window, click on the “Finish” button.

    Click on the “Done” button

Video: how to uninstall Yandex.Browser

Installation of "Yandex.Browser"

Installing a new version of Yandex.Browser is no different from updating and is discussed in detail in the previous paragraph of this article. When installing from an optical storage medium or USB drive, the process is also similar to installing from an Internet source.

Video: how to install Yandex.Browser correctly

Fixing error retrieving browser settings

An error in retrieving browser settings occurs rarely, but it causes some difficulties for users. To fix it, you may also need to update or reinstall Yandex Browser. But before that, you can try deleting the user profile:

  1. Launch Yandex Browser.
  2. When a panel appears with the warning “Unable to obtain settings...”, click on the “OK” button.

    Click on the “OK” button

  3. After the “Yandex.Browser” window appears, click on the “Settings” icon.

    Click the Settings icon

  4. In “Settings” go to the “Profiles” section and click on the “Delete profile” button.

    In the “Profiles” section, click on the “Delete profile” button

  5. Yandex Browser should restart in standard mode. If this does not happen, then uninstall it and install the current version.

Video: removing a profile from browser settings

Removing malware from the system

Malicious programs can block the launch of Yandex.Browser. Virus scanning can be done using the 360 ​​Total Security program. To do this, you need to download and install the application on your computer, and then check your computer for malicious software and remove it:

  1. Launch the antivirus program by double-clicking on the icon on the “Desktop”.

    Double-click the 360 ​​Total Security icon

  2. In the program console, select the “Full Scan” tab on the left side and click the “Scan” button.

    Click on the “Check” button

  3. Wait for the anti-virus scan to complete.

    Wait for the verification process to complete

  4. When the check is complete, click on the “Fix” button.

    Click on the “Fix” button

  5. Any problems found will be fixed. Click on the “Finish” button.

    Click on the “Finish” button

Video: how to remove viruses from your system using the 360 ​​Total Security antivirus program

Disabling your antivirus program

Sometimes an antivirus program causes Yandex Browser to be blocked from launching. To fix this problem, you need to disable your antivirus. In 360 Total Security, protection is disabled by the following steps:

  1. Launch the 360 ​​Total Security program.
  2. In the program console, click on the “Protection: on” icon. in the upper left corner.

    Click the "Protection: On" icon

  3. In the console that opens, click on the “Settings” button.

    Click on the “Settings” button

  4. In the lower left corner, click on the “Disable protection” tab.

    Click on the “Disable protection” tab

  5. Check the launch of Yandex Browser.

If the launch is successful, it is recommended to uninstall and install another antivirus program. You can use Kaspersky Total Security or Dr.Web. You should not install free antiviruses such as Avast, ESET NOD32, Avira or Microsoft Security Essentials. Unlike paid versions, they do not have full anti-virus functionality and very often miss malware.

Video: how to disable 360 ​​Total Security antivirus program

Checking the network connection is working properly

Launching Yandex.Browser depends on the connection to the provider's server. If it is missing, then the reason for this may be a lack of network connection. First of all, you need to check the reliability of the connection between the network cable and the computer system unit.