This error occurs mainly when you are trying to check your email sent summary or email queue or any other function in your WHM panel.
To fix this error you have to follow the below steps.
1). Login to your cPanel server via SSH as root and run the below command to repair eximstats
If it gives this output :
status : Operation failed
Then it means it cannot be repaired and will need to be recreated.
Then run this command :