问题
My TFS 2017 Update 2 on-premise is according to the Marketplace (https://marketplace.visualstudio.com/) running in Connected Mode. Whatever extension I try to install in this mode results in the error message:
Something's gone wrong
We've encountered an error while downloading the extension. Please try again later.
If I try to install the same extension in my VSTS account it works fine.
If I disconnect my TFS on-premise from the Marketplace the "Install" button changes to "Get it free" and I can get to the download page for the extension and get the extension that way.
The error message gives no clue as to where I should start searching for the root case. Is the Marketplace having issues or is the error on my end? Do I need to open a firewall port? Something else?
I have tried this on two separate connected TFS 2017 Update 2 on-premise installations and get the same behaviour. I have TFS Administrator (Console Admin) rights on both.
回答1:
Please check the permissions first to make sure you have the correct permissions to install the extensions:
What do I need to install extensions?
Project collection administrators with Edit collection-level information permissions can install extensions. If you don't have permissions, you can request extensions instead.
Well, I tested on TFS 2017 Update3 (no update2 on my side) while connected to TFS and everything works as expected, cannot reproduce the issue...
However that might be an temporary network issue, so just as the error message said you can try that again later... If the issue persist, then as a workaround you can download the extension from Marketplace and upload to TFS to install. You can also try upgrading to TFS 2017 Update 3, it should work for you.
Refer to Install extensions for Team Foundation Server (TFS) for details.
来源：https://stackoverflow.com/questions/52762033/tfs-2017-on-premise-cant-install-marketplace-extensions-in-connected-mode