TB Sync fails with error http error 500

[bernhardbrunner]

Your environment

TbSync version: 4.8
EAS-4-TbSync version: 4.8
Thunderbird version: 115.16.0esr (64-bit) Debian Linux 12.8

Expected behavior

Synchronisation to Activesync Server

Actual behavior

Synchronisaton fails
Disabling and re-enabling the account hangs with a countdown from 90sec and fails with server error 500
Since i have two accounts on the same server, one of which started working again while the other still fails, I suspected an interaction with state information on the client

Steps to reproduce

Enabling devoloper tools and tracking network traffic showed that the problem was that the OPTIONS retrieval failed transmitting cookie stored by the server

Solution: in Thundebird settings - cookie - search for server url - delete cookies
Reenable the account and verify that options are transmitted without timeout

This is just a quick fix, if the problem reappears I will post more logs.
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To help resolving your issue, enable debug logging (TbSync Account Manager -> Help) and send me the debug.log via e-mail (use the title of your issue as subject of the email).