First of all, let me tell you that I am a 19 year old computer technician working inside the customer service, I saw you customer weren't very happy.
Well after getting the error 210 and 209 for pretty much a while now, I looked up on the forums just to see that the issue is known but there is not really a solution for it, only troubleshooting sometimes happen to solve the problem, I have founded myself, a solution that worked perfectly since I have applied.
Let me start with the fact that before I used my solution, I had to re-install the game completly to play and the next day, I couldn't play anymore because I received the same error as always. The patch manifest error.
But, one day, I searched in the known error database about this error and I tried one of the troubleshooting step, which is to execute the launcher as an administrator.
It worked, perfectly.
Now that I knew it was a problem of permission on the folder and not about the launcher, I changed all my permission as a user (which I hadn't permssion to modify) to total control on the Zenimax Online Folder and then I tried to execute the launcher as a non administrator, still worked.
After thinking, it all came logically to me that the Bethesda.net_Launcher.patchmanifest needed a permission of modification to be runned, so I think it is all about the modify permission on the ProgramData folder at the path :
C:\Program Files (x86)\Zenimax Online\Launcher\ProgramData
Maybe you could try to tell some people about this solution to other customer and perhaps, offer me a job to help with the problem finding and troubleshooting, I am very good at it and I have not many chance to go in deeper problems at my current job at the ministry of transport of Quebec.
Maybe this long lasting error that caused you to loose alot of customer is now fixed, maybe not, but thank you for reading my ticket.