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Since April we started a new EA agreement with Microsoft and added all of our users to E5 licenses of M365 on top of the E3 licenses they already had - we were told that the E3 licenses would disappear anyway.
We don't know if that is related, however since mid-April we started to have numerous users who find their email attachments to get corrupt in Outlook. Whether it's with Outlook 2016 or 365, and Windows 10 or 11 Pro, the symptoms are always the same: the size of the attachments decrease significantly and they cannot be opened in their usual application (Adobe PDF Viewer, Word, Excel, PowerPoint, etc.).
Attachments in emails are oftentimes received already corrupt and are therefore unusable, sometimes they are good to be viewed or opened, then later on get corrupt. Sometimes
the attachments get corrupt when their related emails get forwarded to other users (who also find corrupt attachments in the emails they received).
We noticed that Outlook sometimes get even in a state where no file can get attached to a new email, or no attachment from a received email can get saved on any drive.
Whenever a user tries to open a corrupt attachment, an error message similar to this appear: "there was an error opening this document. The file is damaged and could not be repaired". No useful details get logged in the Event Viewer, all we see at the time of the error is "An unexpected error has occurred".
We tried the SaRa diagnosis program on some users' workstations with no luck, the SaRa program gets to vanish before the issue is seen again.
We tried to run Desktop Outlook in Safe Mode, the issue has not been seen. We tried to disable all of our add-ins one by one in normal mode, the issue was seen with every add-in being disabled....
We have hundreds of users and are out of ideas. Can you please help.
Using Classic Outlook on Windows for personal email, calendar, and contact management
Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.
Our Office 365 version is 2303.
We solved the issue here by deploying the following Known Issue Rollback (KIR) to over a thousand of workstations:
Windows 11, version 21H2: KB5023774 230222_032017 Known Issue Rollback
Windows 10, versions 21H2/22H2: KB5023773 230222_032013 Known Issue Rollback
May Update KB5026361 and April Update KB5025221
We are having the same issue. This first starting happening after the April update went out. There are multiple symptoms sometimes the attachment gets corrupted after sending, other times is gets corrupted after being received. Other users are unable to drag and drop attachments into Outlook. Uninstalling the April update resolved the issue but it has returned after installing May's update. We currently use Cyberark and they confirmed the issue on their end but have no permanent solutions. Additionally I have a ticket open with Microsoft and was working with Outlook team but they just transferred the ticket to the Networking team.
I wonder what the commonality is between Avast and Cyberark that is producing the same issue
Are there any developments on the MS side to find the root cause of this issue. At work multiple users are reporting the problem since April. We use cyberArk EPM but this product has been in place for a couple of years. We have a ticket opened with MS but with no progress. CyberArk vendor provided workaround to disable the cyberArk outlook plugin but referred us to MS of an actual root cause and solution.
Oh wow. I thought I was going crazy.
We're seeing the exact same issue.
I even setup a transport rule to copy any incoming PDF's to a Shared Folder which users can access through OWA to prevent this occuring.
If I hadn't seen it with my own eyes I wouldn't believe it was happening.
User receives a PDF and can view it. Go to forward it on or view it again later and the file size has shrunk considerably and is no longer openable.
If you find a solution, please let me know.