Error: Manifest data not found in archive

Hello wonderful developers!
I have been looking for days, trying to fix the issue I am having, but nothing is working. I have read/tried the solutions I have found on wpmudev threads... but it hasn't worked for me.

I am trying to do a test transfer (from one test site to another test site to make sure the transition to the real deal is smooth), and I keep getting the message "Error: Manifest data not found in archive." I have tried uploading/downloading from Dropbox and File Manager, but I keep getting the error message.

I am not sure what to do differently, but I hope you can help :smiley: