Hi, all -- having the same problem. I can open the ADOBE PDF file in Acrobat Reader, but I cannot open it from Mac Mail -- I get the following error message, even though permissions have been given to Acrobat Reader in the "get info" panel -- this does not seem to happen with ALL pdf files, just some. I like to check the PDF file from Mac Mail before I send it to make sure that it's the right one and that the person receiving it will be able to open it, so this is rather frustrating! Any solutions? I'm running the latest Adobe Acrobat Pro DC on Mac Big Sur. The operation could not be completed as Acrobat Pro DC doesn't have permission to access: ~/Library/Containers/com.apple.mail/Data/Library/Mail Downloads/. Launch privacy settings to grant access?
I have the same problem as well. Harsh, your response is of little use. The original question has nothing to do with OneDrive. It has to do with Apple Mail (mail.app). It appears to be related to a recent OS upgrade Mac OS Big Sur 11.6.6. It is fixed in Mac OS Big Sur 11.6.7 as describe in Apple's release note here which says:
macOS Big Sur 11.6.7
macOS Big Sur 11.6.7 fixes an issue where Mail and apps, such as Microsoft Outlook, cannot open attachments if the app required to open the file is already running.