Configure Veeam Backup for Microsoft Office 365 to use an HTTP proxy

Challenge

An HTTP proxy is required by a corporate security policy, and Veeam Backup for Microsoft Office 365 fails to run any backups or add Office 365 organizations to its scope because of the proxy.

Solution

Currently only non-transparent proxies without user authentication are supported
To make Veeam Backup for Microsoft Office 365 use an HTTP proxy, the following must be done:

1. Using the netsh command, a system proxy must be configured in order for Exchange Online PowerShell to work properly. Please start an elevated cmd.exe and input:

   Netsh
   Winhttp
   Set proxy <proxyFQDNorIP>

2. Ensure that no Backup or Restore jobs are running, then stop both the Veeam Backup for Microsoft Office 365 Service and the Veeam Backup Proxy for Microsoft Office 365 Service
3. Navigate to %ProgramData%\Veeam\Backup365
4. Edit Config.xml, adding <Ews UseSystemProxy="True" /> under <Veeam>, but above <Archiver>
   
5. Do the same thing with Proxy.xml
   
6. Navigate to the Veeam Backup for Microsoft Office 365 installation path (by default %ProgramFiles%\Veeam\Backup365), edit the file Veeam.Archiver.Service.exe.config,and add the following lines under <configuration>:
    

   <system.net>
   <defaultProxy>
   <proxy proxyaddress="http://yourproxyFQDNorIP:port" usesystemdefault="true" />
   </defaultProxy>
   </system.net>

   
   
7. And the same thing for Veeam.Archiver.Proxy.exe.config
   
8. Pay attention to proxy address format – ‘http://yourproxyFQDNorIP’ and ‘port’ are mandatory, otherwise you will see errors like this one
   

If you are using a remote backup proxy, then steps 1, 5, and 7 should also be repeated there, yet Veeam.Archiver.Proxy.exe.config will be in %WinDir%\Veeam\Backup365Proxy.