Here are some solutions you can try to fix the Discord Update Failed error:
Run Discord as administrator. This will give Discord the necessary permissions to make changes to your system and install the update. To do this, right-click on the Discord icon and select “Run as administrator.”
Rename the Update.exe file. This will force Discord to download a fresh copy of the update file. To do this, close Discord and then go to the following folder:
%LocalAppData%\Discord\Update
Rename the Update.exe file to something else, such as Update.old.exe. Then, open Discord and it should start downloading the update.
Disable Windows Defender or your antivirus software. Sometimes, your antivirus software can interfere with Discord’s ability to update. To disable Windows Defender, go to Settings > Update & Security > Windows Security > Virus & threat protection > Manage settings. Under Real-time protection, turn off the toggle switch. To disable your antivirus software, you will need to consult the documentation for your specific antivirus software.
Clear the Discord cache. Sometimes, corrupted files in the Discord cache can cause problems with updating. To clear the Discord cache, close Discord and then go to the following folder:
%LocalAppData%\Discord
Delete all the files and folders in this folder. Then, open Discord and it should start downloading the update.
Reinstall Discord. If none of the other solutions have worked, you can try reinstalling Discord. To do this, close Discord and then uninstall it from the Control Panel. Once it is uninstalled, download and install the latest version of Discord from the Discord website.
Contact Discord Support. If you have tried all of the above solutions and you are still having problems with updating Discord, you can contact Discord Support for assistance. They may be able to help you identify the cause of the problem and provide you with a solution.