Refer to actions/toolkit#1779 (issue fixed in actions/http-client 2.2.2 actions/toolkit#1782)
When checking out a repo using the REST API, proxy credentials with URL-encoded characters are not handled correctly and passed to the proxy server as-is (i.e. with the URL-encoding still in-tact). The proxy server then returns failed authentication error.
Solution: update actions/http-client to 2.2.3 (latest 2.x version)
checkout/package-lock.json
Line 83 in 900f221
Refer to actions/toolkit#1779 (issue fixed in actions/http-client 2.2.2 actions/toolkit#1782)
When checking out a repo using the REST API, proxy credentials with URL-encoded characters are not handled correctly and passed to the proxy server as-is (i.e. with the URL-encoding still in-tact). The proxy server then returns failed authentication error.
Solution: update actions/http-client to 2.2.3 (latest 2.x version)