Fix Adobe Acrobat Cannot Connect to SharePoint Review Server
Question details
Users are unable to check for or publish comments in a shared PDF review because the software fails to connect to the server.
- Product
- Adobe Acrobat / Adobe Reader
- Device & OS
- Windows
- Scenario
- Attempting to sync, check for, or publish comments in an active shared review hosted on a SharePoint server.
- Observed behavior
- The initial shared review publishes successfully, but subsequent attempts to check for or publish new comments fail with a connection error, even though other computers may still be functioning normally.
Ensure you have administrative privileges on your Windows computer, as applying this fix requires ending background system processes and making targeted modifications to the Windows Registry.
Update Software and Modify the Adobe Synchronizer Registry Key
This solution forces Adobe Acrobat to bypass HTTP/2 protocol conflicts with SharePoint by adding a specific bypass rule in the Windows Registry.
Network protocol changes in certain Acrobat updates can cause communication failures with SharePoint servers. Disabling HTTP/2 specifically for SharePoint URLs within Adobe's Synchronizer helps restore the connection.
Open your Adobe software, navigate to Help > Check for Updates, and ensure you are updated to version 19.010.20091 or later. Once updated, completely close the application.
Right-click the Windows taskbar and select Task Manager (or press Ctrl + Shift + Esc). Locate 'AdobeCollabSync.exe' in the Processes or Details tab, select it, and click 'End task'.
Press Windows Key + R to open the Run dialog, type 'regedit', and press Enter to launch the Registry Editor.
In the Registry Editor, use the left pane to navigate to: HKEY_CURRENT_USER\Software\Adobe\Adobe Synchronizer\DC.
Right-click an empty space in the right pane, select New > String Value. Name the new value exactly 'tdisableHTTP2List'. Double-click it and set the Value data to '*.sharepoint.com'.
Close the Registry Editor, restart Adobe Acrobat, open your shared review document, and test the connection to the Review Server.
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Frequently Asked Questions
Why does Adobe Acrobat suddenly stop syncing with SharePoint?
This is often caused by HTTP/2 protocol compatibility issues between the Adobe Synchronizer background process and SharePoint's network configuration, which can be inadvertently triggered after an automatic software update.
What is AdobeCollabSync.exe and why must I close it?
AdobeCollabSync.exe is a background process that manages real-time synchronization for shared reviews. You must forcefully end this task in Task Manager to ensure it stops running and properly reads the newly added registry values when it restarts.
Will reinstalling Acrobat fix the SharePoint Review Server error?
Not necessarily. If the issue is rooted in protocol configurations handling the SharePoint connection, a simple reinstall might not fix it. Applying the specific registry fix for HTTP/2 is usually required alongside having a sufficiently recent version of the software.
