After updating my Norton 360, my IMac refuses to open scanned pdf files

My Imac after updating my Norton 360 refuses to open scanned pdf files from my hp7155 printer / scanner on my LAN, when I double click on them. If i start preview and open the file from preview's file menue it openes in preview. If I "save as" to same file name, I can then open that file by double clickin on it. the dpaslog box opened when its unhappy with the original pdf file is that the signature is unknown

 

"covid-19 immunization report 150dpi.pdf" can't be opened bevuase it is from an unidentified developer.

never had this trouble  before I  updated Norton.

Rick Shiffman

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