mail db had no sync anchor - Error with Activesync

When using the Exchange Activesync with Exchange 2010, numerous users are experiencing full refreshes on the device of the calendar and email. This causes issues as the users are being re-prompted to accept meeting invites and some mail is appearing as unread.

Here is the log below:

Sep 4 08:05:01 MobileMail[637] <Notice>: 0x1d512190|EAS|Warn |mail db had no sync anchor for folderID 61. Will erase local messages, perform full sync.

Sep 4 08:05:03 MobileMail[637] <Notice>: 0x1e8b6b10|EAS|Error|connection died with error Error Domain=ASHTTPConnectionErrorDomain Code=500 "The operation couldnt be completed. (ASHTTPConnectionErrorDomain error 500.)" 0x1e8076d0

Sep 4 08:05:03 MobileMail[637] <Notice>: 0x1e8b6b10|EAS|Error|ASFolderItemsSyncTask failed: Error Domain=ASHTTPConnectionErrorDomain Code=500 "The operation couldnt be completed. (ASHTTPConnectionErrorDomain error 500.)"

Sep 4 08:05:03 MobileMail[637] <Notice>: 0x1e8b6b10|EAS|Error|connection died with error Error Domain=ASHTTPConnectionErrorDomain Code=500 "The operation couldnt be completed. (ASHTTPConnectionErrorDomain error 500.)" 0x1e8076d0

Sep 4 08:05:03 MobileMail[637] <Notice>: 0x1e8b6b10|EAS|Error|ASFolderItemsSyncTask failed: Error Domain=ASHTTPConnectionErrorDomain Code=500 "The operation couldnt be completed. (ASHTTPConnectionErrorDomain error 500.)"

Sep 4 08:05:03 MobileMail[637] <Notice>: 0x1d512190|EAS|Warn |server returned null sync key for sync of folderID 61. Will erase local messages, perform full sync.

Sep 4 08:05:07 MobileMail[637] <Notice>: 0x1e8b6b10|EAS|Warn |Erasing locally cached messages for folderID 61

The users are very

TMG Version

7.0.9193.575

Exchange 2010

14.02.0347.000