We are sorry for the trouble. As described you are getting the error 'Object lable badly formatted'
What is the workflow/steps you are doing to open the PDF form the particular site?
Is this a behavior with a particular PDF file or with all the PDFs that you try to open? Please try with a different PDF file and check.
If the PDF is stored on a shared network/drive, please try to download the file locally to your computer and then try to open it with Adobe Acrobat/Reader DCand check.
You may also try to turn off the protected mode for testing. Go to Edit > Preferences > Enhanced Security > Uncheck 'Enable protected mode at statrtup', Turn off the protected mode and uncheck the enhanced security > Click OK and Reboot the computer and check. Note: Turning off the security may possess security risk. Please turn on the security after testing.
If turning off the security works for you. Please try to add the file and the folder path to Adobe Acrobat/Reader DC. Go to Edit > Preferences > Enhanced Security > Add File and Add Folder Path > Click Ok and reboot the application.