Running the PowerServer Web APIs and then Fiddler – PB Docs 2022

Be sure to run the PowerServer Web APIs before you start Fiddler
(or any other Web debugging proxy tool). Otherwise, the PowerServer Web
APIs will fail to start.

Reason is Fiddler (as well as any other Web debugging proxy tool)
works by adding itself as a proxy instead of using your current proxy
settings; therefore it will change your proxy settings on startup and
reverts them back to what they were when Fiddler is closed. If the
PowerServer Web APIs connects with the NuGet site and Appeon site
through a proxy server, it may fail to start.