Users are unable to attach files in Outlook and other Office applications (from local drive or OneDrive)

Question

Users are unable to attach files in Outlook and other Office applications (from local drive or OneDrive)

Pejman Minooei 60

Since applying the June 2026 updates, we are experiencing a critical issue with file attachments in Microsoft 365 Apps. (Outlook classic).

Affected versions:

Version 2610 (Build 20527.20196)
Version 2610 (Build 20527.20150)
Version 2610 (Build 20527.20112)
Version 2610 (Build 20527.20088)

Issue: Users are unable to attach files in Outlook and other Office applications.

Workaround: Rolling back to Version 2605 (Build 20026.20166) fully resolves the issue. We have also stabilized the environment by disabling automatic updates and enforcing the previous version via XML configuration.

Impact: Organization-wide disruption affecting client communications (High severity).

Request: Please investigate the root cause of the attachment issue in Version 2606 or higher version 2610, confirm whether this is a known issue, and provide a timeline for a fix along with a recommended long-term solution.

Best Regards.

0 comments

1 answer

Your answer

Answer 1

Hello @Pejman Minooei

Thank you for providing those details.

Based on the information available, there is currently no public documentation or release note confirming this as a known issue in the affected Microsoft 365 Apps builds, and no official fix or timeline has been published at this time.

Since rolling back to Version 2605 (Build 20026.20166) consistently resolves the problem in your environment, I would recommend continuing to use that rollback as a temporary workaround while keeping automatic updates paused, as you have already done.

Since the issue affected multiple users and has business impact to your tenant, as a Microsoft Community Moderator, I don't have direct influence over Microsoft's product development team or Microsoft support team. However, customer feedback is actively reviewed by Microsoft and may help influence future prioritization and support resolving such cases. I would recommend you to raise the case to the Microsoft support team for further investigation on the case and provision of support.

Thank you for your cooperation.