Update WordPress failed

Hello. I wanted to update WordPress and I got the following message: “The update could not be installed because some files could not be copied. This is usually due to inconsistent file permissions.”

I reconfigured all the permissions to 775 and 644, in case any had been modified. The error was not resolved.

I don’t know what I could do to solve the problem. I can update plugins without a problem, it is only WordPress itself that I cannot update.