hi @a_suvorov and first welcome to Rstudio Community.
Can u more explain your issue and post a ReprEx. It will help us to help you.
If it a non-programming help see how to do so here:
Project is "Opening" for already 48 hours.
Relaunch attempts gives error 409 "Conflicting task in progress".
There was some maintenance last saturday!!! See status here. https://status.rstudio.com/
Maybe it affect your project!! Can u close and re-open your project
There was an issue with one of our servers that effected your project. The issue has been repaired, so this project should be working fine now. Please let us know if thats not the case. Sorry for any trouble this might have caused.
Now everything works!