Event ID: 8088
Event Description: The Managed Metadata Service 'Managed Metadata Service' is inaccessible.

Not a very detailed error.  ULS does not expand on the error either.  I ensured that the MMS Service Account has full control to the service.  I also put the account in the Term Store Administrators but that did not fix the issue.  I reset the MMS on all servers in the farm as well, no luck.  

Any ideas?

Please check application pool which is responsible for processing MMS.

Regards.

Did you ever find a fix for this?  I get this error about once a week and I can't figure out what I can do that will make the error go away.....

Might be a long shot, but does the service account used to run the MMS have its password set to expire? I saw this occur when the service was installed with a user account, then their password expired. Definitely not best practice, but once we found out what was wrong, we changed the identity to a dedicated service account and all worked again.

Nope, it runs under a SG that is not going to expire soon, as I said it happens intermittently...  any other thoughts on how I  can get rid of this error?  Is this error indicative of something bad happening?  When I get the error, I log in and evertying appaers to be normal/happy/running.

Any thoughts on this would be great!

Thanks,

Cindy

Did anyoen find a answer for this I am seeing the same thing on sevral farms, says its bad but, it is running just fine

Hi, I have exacatly the same issue. with all the accounts granted the right permission on the metadata service

Hi,

Verify the application pool account permissions.

Reference: http://technet.microsoft.com/en-us/library/ff383250.aspx

Br,

Ani

We've got this issue on Production SharePoint 2013 a few times in the past few months.  To resolve, we just did IISRESET, but I'm trying to determine cause to prevent from happening again

We are using MAnaged Metadata Navigation, so it caused our site to 'error'/not load

HI,please check the links below that explains more in details about the issue and the solution for this.

http://expertsharepoint.blogspot.de/2014/08/managed-metadata-service-or-connection.html

http://expertsharepoint.blogspot.de/2013/10/issue-metadata-service-is-unavailable.html