Agent log shows CPersistJet::GetIdByExId Error 3800 'idx_session_exid' is not an index in this table (4351450)

Mail agent reports the following error:

"4/26/2011 5:43:02 PM CAgentStat::CPersistJet::GetIdByExId Error 3800 'idx_session_exid' is not an index in this table. ExId:174C1225F3DB914494C3FF82ADBF42DA, DisplayName:MTA:: Session 4/26/2011 9:43:02 PM
4/26/2011 5:43:02 PM CAgentStat::ReleaseSessionEx InternalError 91 Object variable or With block variable not set"

Those entries are logged by the Statistics Collection Agent (CAgentStat ) and they usually don't affect the work of the mail agent, MSA or MTA can still process data, but statistics data will not be collected

Reinstalling the Mail agent will also create a new emwstat.dat and this step will resolve the issue

However reinstalling a working agent just in order to resolve this issue is not always desirable.

As workaround the following can be tried:

-stop the agent
-find and rename or delete the old emwstat.dat file
-copy the attached to this article emwstat.dat file, it is valid for any version of the tool and for any agent.
-Start the agent and then the agent will populate the emwstat.dat file with data.

Important: using both approaches (reinstalling the agent or replacing the dat file) will result in some statistical data loss and as end result in somewhat inaccurate (incomplete) statistics. This can be resolved by performing a full resynchronization of mail data.