Outlook Shared Calendars Showing "Cannot Be Updated"

This is a running issue in certain places where Microsoft Exchange is hosted on site.  A user will share their calendar and the recipient won’t be able to see it because the calendar will show “cannot be updated” or some similar message on the Calendar tab.
There are a lot of fixes for this out there that might work. One is to set Outlook in Cached Mode, or take it out of Cached Mode and put it back. Sometimes this works, sometimes it doesn’t.
What I was able to track down was that the account doing the sharing sometimes gets corrupted on the Exchange server itself. The default calendar’s sharing permissions get messed up somehow and must be set back to defaults.

How to Fix Outlook Shared Calendars Showing “Cannot Be Updated”

Step 1 – Log into your Exchange Server and Open the Exchange Management Shell. It’s the Powershell with the orange icon behind it.

Step 2 – Enter the following command:

Get-MailboxFolderPermission -Identity username:\calendar

You should get a readout that looks something like this:

RunspaceId : 18b6bb25-14bf-40cc-9843-c76c4d2f5116
FolderName : Calendar
User : Default
AccessRights : {AvailabilityOnly}
Identity : Default
IsValid : True

There might be a bunch of other stuff on there but the first group should be the default. What you’re looking for is the “Access Rights” row. If it says {None}, there’s a good chance that’s part of your problem. If it says LimitedDetails or AvailabilityOnly, you probably have another problem.

Note – username could be the person’s windows login name, an email address or an alias, you might need to experiment a little to figure out what it is for your environment.

Step 4 – Once you’ve determined whether this is your problem or not type the following:

Set-MailboxFolderPermission -Identity username:\calendar  -User Default -AccessRights AvailabilityOnly

Note- I noticed that on Microsoft’s site there was a space between :\ and calendar. I was given an error when I typed it like that, but not when I excluded the space. The article was for Exchange 2010, so I’m not sure what the problem was. Also the article I referenced this code from used an email address as the Identity, that did not work for me with either Get or Set Mailbox Folder Permissions. I suspect it is different depending on environment. I also do not know if “Default” should be capitalized, I suspect not.

You can also change the “AvailabilityOnly” to “LimitedDetails”, that’s just the default on all the Exchange Servers I work with.

This seems to fix some of the weirder cases of this problem. The recipient user may need to close Outlook, re-add the calendar, wait a while, or reboot but it does seem to work.
If this doesn’t correct the problem, it will at least correct a permission issue that isn’t obvious on your server.