Backup-Job Error after upgrading to 8.4 (Index was outside the bounds of the array.)

[aeph]

After upgrading our environment to latest Version (8.4.0.1457) we are getting job errors with this type of message:

ERROR: Failed to process site: XXX. Index was outside the bounds of the array.

And some warnings:

WARNING: Processing team files: XX completed with warning: Index was outside the bounds of the array.

At the moment just teams and sharepoint is affected. Not all sites and teams of a organization is affected.

Also quite strange: Veeam M365 automatically performed a full backup for one of the affected organizations, but this did not resolve the issue. We retried the job several times, yet many errors still remained.

The next day, the errors for this organization were gone, but new organizations were affected instead. After another retry, we were able to successfully complete the daily backup for all organizations.

We are managing around 40 organizations, so it requires significant effort to continuously monitor the status and rerun jobs whenever errors occur.

Someone experiencing the same issue?

Whats interesting: We had this error (veeam-backup-for-microsoft-365-f47/erro ... 02969.html) on some sharepoint sites (400+) and this error seems to be gone.

Case ID: #08080618