How to Fix FileCoAuth.exe – Application Error on Windows?

The FileCoAuth.exe – Application Error appears when the OneDrive/Office co-authoring tool fails to start or suddenly crashes. This small program helps Word, Excel, and PowerPoint update shared files in real time when they are saved in OneDrive or SharePoint. When it stops working, shared documents may not update properly, and you may lose live collaboration features.

FileCoAuth.exe normally runs quietly in the background from the OneDrive installation folder (for example: %LocalAppData%\Microsoft\OneDrive). Windows starts it automatically whenever a file needs real-time editing.

Most people see this error during startup or right after a crash while OneDrive tries to restart the service again and again. During this time, you might see repeated pop-ups, File Explorer may freeze or lag, your desktop may stop responding for a few seconds, and some apps can become slow. Co-authoring stays disabled until the issue is fixed.

Common causes of this error include:

• Malware pretending to be FileCoAuth.exe.
• Low or failing disk space causing Windows to slow down or fail to load needed files.
• Corrupted OneDrive files or broken registry entries.
• Issues with Windows cryptographic services that verify program signatures.
• Repeated crash loops caused by damaged or missing files.

In most cases, the problem happens because of low storage space, damaged OneDrive cache files, or an outdated version of Windows/OneDrive. When your disk is almost full, FileCoAuth.exe may crash more often.

1. Restart Your PC

A simple restart fixes many temporary errors, clears memory, and stops crash loops.

1. Open the Start menu.
2. Click the Power icon and choose Restart.
   
3. After restarting, check if the error appears again.

2. Free Up Storage

If your Windows drive is almost full, OneDrive may fail to load important files. This can cause FileCoAuth.exe to crash. Try to keep at least 15–20% of your drive free.

1. Open Task Manager (right-click the taskbar → Task Manager).
   
2. Pause or end OneDrive if needed.
3. Open File Explorer and delete or move large unneeded files from:
   • Downloads
   • Desktop
   • Documents
   • Local OneDrive folders
4. Free at least 10–20% of the drive.
5. Restart OneDrive and check the error.

3. Run a Full Virus Scan

Malware can copy or replace system files, including FileCoAuth.exe. Running a full scan helps remove anything harmful.

The real FileCoAuth.exe is only found inside the OneDrive folder. If you see it anywhere else, treat it as suspicious.

1. Press Windows + I → open Settings.
2. Go to Privacy & Security → Windows Security.
   
3. Open Virus & threat protection.
   
4. Select Full scan and click Scan now.
   
5. Remove any threats and restart your PC.

4. Run SFC and DISM (Repair Tools)

Damaged Windows system files can break OneDrive’s co-authoring system. These two tools help repair them.

1. Search for CMD, right-click, and choose Run as administrator.
   
2. Run this command:

   DISM.exe /Online /Cleanup-image /Restorehealth

3. Then run:

   sfc /scannow

Restart your PC after the repair completes.

5. Update Windows

Older versions of Windows or OneDrive may contain bugs that cause frequent FileCoAuth.exe crashes. Updating helps fix these issues.

1. Open Settings.
   
2. Click Windows Update.
3. Click Check for updates.
4. Install all available updates and restart if required.