BOINC does not yet know the new address, so you will need to reattach directly AND manually add the "s".
since many weeks I get this message too:
Quake-Catcher Network: Notice from BOINC
This project is using an old URL. When convenient, remove the project, then add https://quakecatcher.net/sensor/
how to change that? or what to do? where to do? tried many things and looked through everything (so I think). But nothing found to change.
This is a notice from BOINC NOT BAM !
So open the BOINC manager and do what they say.
When the manager opens, click on meny 'show' (second from the left near the top) and if 'advanced' is available - click on it. If it is not available , you are already on 'advanced'.
Click on 'projects' tab.
Here you can see the projects you are attached to.
Click on 'Quake Catcher'.
In the left column click on 'remove'.
When it has been removed click on meny 'tools' (fifth from the left near the top).
Click on the first entry 'add project'.
Now you can copy/paste the address from your error message into the URL box.
Then click 'next', choose 'existing user' and follow instructions.
Good luck with --- When convenient, remove the project, then add https://quakecatcher.net/sensor/