There was an error downloading metadata from the address

Question

I am trying to add service reference.

There was an error downloading metadata from the address

this is the error which is being displayed again and again?

Answer 1

I know this is an oldie, but I thought I would add what worked for me so that I can find it again down the road ;)

In my case, the AppPool user didn't have access the %Windir%\temp, which apparently is necessary in order for the MEX data to be generated.

Shout out to Amy Peng in this thread for her tip!