One of our customers wants to share his calendar with the whole company. He set up permissions in Outlook but users had inconsistent ability to connect or see his calendar, so we went in and removed every extraneous permission, leaving only "Default" and then set the "Default" to have "Reviewer" access rights. This seems to have worked for most of the office, but a few users are still unable to access this calendar. All users are in the same organization, AD Domain, etc.

When opening the calendar in Outlook, the calendar displays a "no connection" message next to its name. Just like this screenshot robbed from the web:Screenshot!

There are no other errors. "Sync Issues" folder has errors, but they're permissions errors for a different calendar completely unrelated to this one.

We've checked everything the web recommends, including verifying that encryption is enabled on the account, rebuilding the connecting user's Outlook profile, verifying that AutoDiscover is working and that all of the internal/external URLs & virtual directories are configured correctly, adjusting up the RCA and CPAMaxConcurrency settings to 40, checking the SSL certificate on the Exchange server is valid, verifying that there are no conflicting delegate permissions, and removing and re-adding the "Default" permission. So far nothing has worked.

We can open the calendar in OWA and we can only view free/busy information, which indicates that it is a permission error of some kind.

Get-MailboxFolderPermission -Identity user@domain.com:\Calendar | fl


RunspaceId   : [GUID]
FolderName   : Calendar
User         : Default
AccessRights : {Reviewer}
Identity     : Default
IsValid      : True

I'm not sure where else to look for an explanation of what's going on. I'm working with one user right now who has this problem, though a few other users also have the same error. Running Exchange 2010 v14.03.0389.001 (Update rollup 20).


  • How many account will access this calendar? For now, I suppose it might exceed the limitation of EWS request by throttling policy. You can run "Get-ThrottlingPolicy | FL EWS*" to check, also check more information in Application log. – Jianfei Wang Apr 20 '18 at 3:21
  • My research had identified throttlingpolicy as the issue, but the references I found said to change CPAMaxConcurrency. From your suggestion I've also applied the same setting (40) to EAS & EWSMaxConcurrency. Gotta check back with the user to see if this works. – Thomas Apr 23 '18 at 20:51
  • adjusting EWSMaxConcurrency to 40 (from 10) made no difference. – Thomas Apr 24 '18 at 15:01

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