Unable to save pdf or reduced PDF (Adobe Acrobat)

[Mark294860603jee]

How can i fix after receiving the follwoing error message? Using iMac 

"The file may be read-only, or another user may have it open. Please save the document with a different name or in a different folder."

[gary_sc]

Have you tried giving it a different name or placing the file into a different folder?

If so, what happened?

[Mark294860603jee]

i have and it still says the same thing. this started when the recent upgrade happened.