I cant seem to generate a .err file aswell after closing the sim.
You are not supposed to have a new .ERR file if you enabled Logging, those will end up in the Couatl.LOG file. I see you attached it renamed as .BGL, you should have ZIP-ed instead. However, that doesn't matter.
Nothing in your log indicates any error. It only shows "server invalid data", because it seems you posted a log of a session in which you had no error, but you used the "Check for updates" function, which check for updates from within the sim.
That error is not really a problem, and it's only temporary, but it won't cause any issues, other than not being able to read the release notes from inside the sim.
However, you said GSX is crashing, that doesn't have anything to do with that error so, if you get a crash, you should quit the sim ( reply NO when asked if you want to Restart the Couatl engine!!! ) and get the LOG from that session, if you restart, the LOG will be overwritten with a new one.
And, don't rename the log but, instead, ZIP it before attaching it.