Symptoms

O365 Exchange online backupset with errors for few user mailbox: "ErrorImpersonateUserDenied:The account does not have permission to impersonate the requested user"


Debug error :


EOLPlugin - 40110098 : Failed to Backup some items in Exchange Online:

40110075 : Retry time : 4

40110076 : Will retry again in (milliseconds). 44267

EOLPlugin - BackupItems Request/Response Mailbox@domain.com The remote server returned an error: (500) Internal Server Error.

An exception occurred in backup. Backup was unsucessful. The following exception has occurred. The remote server returned an error: (500) Internal Server Error.

Failed to Backup some items in Exchange Online:

Cause

1. Backup user doesnot have permissions on the mailbox

Workaround

1. Verify the backup user is 'Global Admin', added to Organisation and Discovery Management, both with role 'Application Impersonation'.

2. Contact AssureStor support to apply the HF18 hotfix.