The main cause for "Maximum Request Length Execceded" errors is when theres an Incident collection on an object, normally the Group object. The attached script will scan the database for any instances of this collection and tell you which object its on.
Execute the attached script against your database, it will return a table lsiting the objects that have an Incident collection on.
You can then remove the collections as normal in Console to improve performance.
ITBM all versions