Unable to Flag

Mail
1

Whenever I either flag or not flagging an email, an error popup will come up. Log details as below

14:27:31   MailExceptions.OperationException: Error in client/server conversion.
14:28:06 EmClient [AirSync]  Synchronizing folder list
14:28:07 EmClient [AirSync]  Synchronizing folder ‘EmClient/Outbox/’
14:28:07 EmClient [AirSync]  Synchronizing folder ‘EmClient/RSS Feeds/’
14:28:08 EmClient [AirSync]  Synchronizing folder ‘EmClient/Sent/’
14:28:08 EmClient [AirSync]  Synchronizing folder ‘EmClient/Sync Issues/’
14:28:09 EmClient [AirSync]  Synchronizing folder ‘EmClient/charley/’
14:28:09 EmClient [AirSync]  Synchronizing folder ‘EmClient/vanita/’
14:28:10 EmClient [AirSync]  Synchronizing folder ‘EmClient/vijay/’
14:28:10 EmClient [AirSync]  Synchronizing folder ‘EmClient/Trash/’
14:28:11 EmClient [AirSync]  Synchronizing folder ‘EmClient/Drafts/’
14:28:12 EmClient [AirSync]  Synchronizing folder ‘EmClient/Inbox/’
14:28:13 EmClient [AirSync]  Synchronizing folder ‘EmClient/Junk E-mail/’
14:28:13 EmClient [AirSync]  Synchronizing folder ‘EmClient/CompletedGCO/’
14:28:14 EmClient [AirSync]  Synchronizing folder ‘EmClient/Sync Issues/Conflicts/’
14:28:14 EmClient [AirSync]  Synchronizing folder ‘EmClient/Sync Issues/Local Failures/’
14:28:14 EmClient [AirSync]  Synchronizing folder ‘EmClient/Sync Issues/Server Failures/’
14:28:15 EmClient [AirSync]  Synchronizing folder ‘EmClient/Trash/samples/’
14:28:16 EmClient [AirSync]  Synchronizing folder ‘EmClient/Inbox/’
14:28:16 EmClient [AirSync]  Synchronizing folder ‘EmClient/Calendar/’
14:28:16 EmClient [AirSync]  Synchronizing folder ‘EmClient/Contacts/’

Another error popup will also come up when I try to categorize an email. Log details as below :

14:30:32 EmClient [AirSync]  Uploading item(s) to folder ‘EmClient/Sent/’
14:30:33   MailExceptions.OperationException: Error in client/server conversion.

My version is 6.0.22344.0

2

Hello, I’m afraid this is a common AirSync protocol issue, that’s unfortunately not possible to workaround from our side. Can you please try to update your eM Client to this release, 6.0.22774.0 and check if the issue persists? 
You can also try to perform a folder repair on the affected folder, which seems to be your sent folder (or the folder where you’ve flagged the message), to repair the folder right click the folder in the left pane and navigate to it’s properties.

Please note that the repair option essentially resynchronises your folder with the server, e.g. removes the locally saved data and resynchronises with what’s available on the server.

Hope this helps,