Veeam Agent OneDrive Backup fails with Key not Found

Challenge

A Veeam Agent backup job targeted at the Microsoft OneDrive cloud storage fails with the following error:
Key not found Failed to establish connection to OneDrive Agent failed to process method {Cloud.AddConnection}. 

Cause

The issue occurs because of some recent changes in the Microsoft Graph API.

Solution

To resolve the issue, apply the hotfix as follows:

1. Download the hotfix.
2. Stop all Veeam Agent services through the following PowerShell command:

   Get-Service -DisplayName "Veeam*" | stop-service

3. Rename the following files: 
   • C:\program files\Veeam\Endpoint Backup\Veeam.Backup.Core.dll to C:\program files\Veeam\Endpoint Backup\Veeam.Backup.Core_original.dll
   • C:\program files\Veeam\Endpoint Backup\x86\VeeamAgent.exe to C:\program files\Veeam\Endpoint Backup\x86\VeeamAgent_original.exe
   • C:\program files\Veeam\Endpoint Backup\x64\VeeamAgent.exe to C:\program files\Veeam\Endpoint Backup\x64\VeeamAgent_original.exe

4. Copy the DLL and the VeeamAgent.exe files from the fix folder to the corresponding location, minding the architecture of the Agent host OS.
5. Start Veeam Agent Services through the following PowerShell command:

Get-Service -DisplayName "Veeam*" | start-service

More Information

[[DOWNLOAD|DOWNLOAD HOTFIX|veeam.com/download_add_packs/backup-agent-windows/kb3139]]

MD5: 932fd6a11e3e6af71b3b0866587b1549
SHA-1: 4c59bd38f550d0a02b639f0d41a951ed5c802ead