How Can I Reduce The Size Of Aspnet.applicationcookie And What's In It?

In our production environment (only) any Admin account has a good chance of receiving 'HTTP Error 400. The size of the request headers is too long.' on just about any request. Loo

Solution 1:

What is in this cookie? (aside from 'authentication stuff')

All the user Identity stuff. Including anything that may have been put in via custom Claims.

What can I do to reduce it's size?

Remove some of the custom Claims.

What could cause prod to be so different?

Data!! Prod has way more data than Dev.

So apparently who ever wrote this particular gem didn't know (or didn't care) that the claim data got stuffed into a cookie and passed around. 'They' put a list in there that will grow with time. Removed and solved.