Thanks so much for the response!
I tried changing the file permissions as you said, but it hasn’t made any difference and I’m still getting the same error message for the Media Library. I also tried changing permission on different file within the directory and some of the other wp directories, but nothing new.
Any other ideas? I can’t help but think it must have something to do with there files I’m trying to upload are stored or the server computer, but neither of these have changed recently so I don’t know why that would make a difference.