Open URL generates error 5

I have an inherited solution where I am working with a View Document script. 

 

The script uses Open URL with the following URL:

 

file:///var/folders/bh/5s1s45p92r3c0gjjhmtzdzgr0000gn/T/supercontainer_downloads_darrenburgess/PDoc/8142/filename=%22test.jpg%22

 

This URL is generated by the SCDownload function in a previous step and does not return ERROR.

 

The URL does appear to be a valid path on the local machine, and there is file named 'filename="Test.jpg" ' in that location and this file appears to be a valid JPG file, although it lacks an extension.

 

See attached screen shot of the script steps in question.

 

Please advise regarding how to resolve this issue.