Previous to this Werk most data changing requests needed a transaction id. This
mechanism was not used in all methods and in some cases the transaction id
mechanism was not a good fit. So now a new CSRF token is introduced and checks
are implemented in various locations.
If you scripted the UI you need to parse the CSRF token from the HTML and send
it with the Post requests.
Please note: Updating to 2.0.0p26 or newer is a compatible change. You don't have
to do anything. However, this change introduces new data fields in the user sessions
which makes this change "incompatible" in case you want to downgrade to an older
version. In case you have to do it, you will have to clean up all files in
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