I hate to say this again (trying to stay friendly here), but every week or two I run into login issues. Today, once more, MSFS 2024 asked me to continue with my Microsoft account. I confirmed, started the sim via the Xbox app, and was rewarded with several “file cannot be saved – error 2000” messages.
When it finally decided to load, it acted as if I had just installed MSFS 2024 for the very first time on this PC. What a mess.

I have a similar issue.  Right after the simulator updated to SU4, I started to receive Error Code 2047 messages all over.  I posted this on a separate thread but no responses yet.  I did open a ticket with MS Support and the bot responded with instructions on how to re-install the sim.  I hope there is an easier fix cause re-installing would be painful with all the addons and such.

I have exactly the same issue as Harrry (Nemo). Has anybody found a fix for it?

Yes. The fix is to completely uninstall MSFS2024 and reinstall it from scratch.  It is the solution provided by Microsoft and unfortunately, the only one that seem to work to resolve the issue.  A complete pain to go through.  I recommend you read all the recommended procedures and backups in this forum and in Youtube before you embark on doing this.  Hope this helps!

For me it worked answer by Google Gemini AI: For GPU-related issues (often seen with crashes, not just Error 2000), edit HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers to set TDR Delay and TDR Level to zero (Hexadecimal or Decimal) and restart PC.

Omg this is the 3rd time I needed to edit registry or some other advanced technical level stuff to keep this game running. Im asking myself ''WHAT'S THE RELATION BETWEEN GRAPHIC'S DRIVERS AND CLOUD SAVEGAME????" But after all that was the solution for me! This game have so bad developers and/or management team! They make problems with each update and never fixing it in updates after last one.

I got error code 2000. What I did to solve it was to install the newest nvidia drivers and do a clean install which removes your old drivers.

I just purchased MSFS 2024 and upon initial installation receive the following error messages:

First error - a syncing error which ultimately presents a dialog box giving me two option buttons: "STOP SYNC" or KEEP TRYING"

Second error - the Error code 2000 dialog box

I have uninstalled the simulator and then attempted to re-install the simulator with the exact same results.  Quite frustrating that I have not been able to open the simulator once after purchase.  I am switching from XP11 to MSFS and this is clearly not a good start.  Additionally, just purchased a new Alienware Area-51 PC with the Intel Ultra 9 285K, RTX 5090, 64 GB RAM,  etc. to run MSFS.  Per the Alienware Support Center, all drivers on my PC are up to date (although not sure if Dell is current with GPU driver updates). Further, I have a wired internet connection with 300 mbps speed (from local cable tv provider). 

Not sure if there are any troubleshooting steps other than mentioned above but thought I would ask nonetheless.  Thank you.