A site running for years suddenly doesn´t work as it used to

I had a problem with en e3arlier version of Revolution, where I could not update templates. I upgraded to the latest version, but the problem still is there. I can´t update templates, or create new a new one. When I save it, an image from the server is flashed for a second, but it does not save. The log does not say anything.

I have checked the time setting on the server, and it does match the time setting in Modx.

Any ideas what is going on here?

Sounds like your hosting provider updated his servers. This sounds like an issue involving mod_security.

Thanks. Will try and find out if they have done some upgrades on mod_security