“The administrative limit for this request was exceeded” When Enabling User for Exchange UM

Recently I was bulk enabling users for Exchange Unified Messaging for users on 2010.  For just a few of the users, I received the following error message when trying to enable them for UM:

Error: Unable to save Unified Messaging PIN for mailbox xxxx: The administrative limit for this request was exceeded.

After using my favorite search engine, I came up empty on this exact error message.  I did get a few hits on the generic “The administrative limit for this request was exceeded” message. 

After a little research, signs were pointing me to the AD user account had a “runaway” attribute with too many entries in it causing other applications to fail when making changes to other attributes.  I reviewed one of the problem user’s attributes and found the userCertificate filled with a bunch of entries.

 

After clearing out the userCertificate attribute the mailbox was able to be UM enabled.

Hope this helps someone else.