Fix Windows Could Not Connect to System Event Notification Service

If you see “Windows could not connect to the System Event Notification Service” when you start your PC, the fix is usually to restart the SENS service and set it to start automatically, then re-register its DLL files. This error typically appears on Windows 10 and 11 after a recent update, a corrupted system file, or a change in service permissions, and it can cause problems with logging in, network connections, and the Start menu.

What Is the System Event Notification Service?

The System Event Notification Service (SENS) is a Windows service that tracks system events—like network connections, logon/logoff, and power state changes—and notifies other components when they happen. For example, when you plug in a USB drive or connect to Wi-Fi, SENS tells the relevant apps and services so they can react. If SENS is stopped or not working, Windows may fail to load your desktop properly, show the error, and leave you with a black screen or a missing taskbar.

SENS runs as a background service (svchost.exe) and is set to start automatically by default. It depends on the Remote Procedure Call (RPC) service and the Event Log service, so if either of those is disabled or corrupted, SENS can fail to start.

Why Does This Error Happen?

The most common causes are:

Recent Windows update that changed service settings or introduced a bug.
Corrupted system files (e.g., from a failed update or disk error).
Malware or a security program that disabled the service to prevent notifications.
Manual changes to the service startup type (e.g., set to “Manual” by a “tuning” tool).
User profile corruption that prevents the service from starting properly.

Sometimes the error appears only once and then goes away, but if it persists, it can prevent you from logging in or using the Start menu.

How to Fix It: Step-by-Step

Try these fixes in order, starting with the simplest.

1. Restart the SENS Service

Press Win + R, type services.msc, and press Enter.
Scroll to System Event Notification Service.
Right-click it and select Restart. If the service is not running, right-click and choose Start.
Right-click again, select Properties, and set Startup type to Automatic.
Click Apply and OK.

If the service fails to start, check the Event Viewer (Win + R, type eventvwr.msc) under Windows Logs > System for details about the failure.

2. Re-register SENS DLL Files

Open Command Prompt as administrator (right-click Start > “Command Prompt (Admin)” or “Terminal (Admin)”) and run:

regsvr32 sens.dll
regsvr32 sensapi.dll
regsvr32 srrstr.dll

You should see a success message for each. If you get an “access denied” error, make sure you are running as administrator.

3. Run System File Checker and DISM

Corrupted system files can cause SENS to fail. Run these commands in an elevated Command Prompt:

sfc /scannow

Wait for the scan to finish (it can take 15-20 minutes). Then run:

DISM /Online /Cleanup-Image /RestoreHealth

Restart your PC after both complete.

4. Check Dependencies

SENS depends on the Remote Procedure Call (RPC) and Event Log services. Open Services (services.msc) and make sure both are set to Automatic and are running. If they are not, start them and then restart SENS.

5. Perform a Clean Boot

A third-party program might be interfering. Perform a clean boot:

Press Win + R, type msconfig, and press Enter.
On the Services tab, check Hide all Microsoft services, then click Disable all.
On the Startup tab, click Open Task Manager and disable all startup items.
Restart your PC. If the error is gone, re-enable services and startup items one by one to find the culprit.

6. Create a New User Account

If the error only appears for one user, the profile may be corrupted. Create a new local user account (Settings > Accounts > Family & other users > Add someone else to this PC) and see if the error occurs there. If it doesn’t, you can migrate your files and settings.

What If None of These Work?

If the error still appears, try a system restore to a point before the issue started, or use the “Reset this PC” feature (Settings > Update & Security > Recovery) which reinstalls Windows while keeping your files. If you have important data, back it up first.

Frequently Asked Questions

Why does the error appear at every login?

If SENS is set to “Manual” or “Disabled,” Windows will try to start it at login but fail, showing the error. Setting it to Automatic and ensuring it starts correctly should fix it.

Can I disable SENS permanently?

No. Disabling SENS can cause system instability, including problems with network connections, logon notifications, and the Start menu. It is a core Windows service and should be left enabled.

Will this error damage my computer?

No, the error itself is not harmful, but it can prevent you from using your PC normally. Fixing it is important to restore full functionality.

Do I need to reinstall Windows to fix this?

Usually not. The steps above resolve the issue in most cases. Reinstalling is a last resort if the system files are too corrupted to repair.

Is this error related to a virus?

It can be, if malware has disabled the service. Running a full antivirus scan is a good idea, but the error is more commonly caused by system corruption or a recent update.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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