It seems to me that the servers are overbooked (maybe because they are also engaged on the 2024 release)! The notice “Checking for updates” should be changed into : “Checking for updates, there are no slots available for you now. try later”
All the suggested workaround have one common base : Time delaying. They keep you busy trying to implement them and,once you have done the job you relaunch the Sim and it may work if a slot became available in the meantime.
In the last 3-4 days I did relaunch the sim several time until it worked.Without workarounds.Just time…matters.