Moving this bug to POST for triage into Satellite since the upstream issue https://projects.theforeman.org/issues/32192 has been resolved.
Tested on Sat 6.10 Snap 13.0 I have configured a Squid HTTP proxy with the a user password "test]satellite@password+". I was able to successfully complete following tasks: - create an HTTP proxy item in Infrastructure -> HTTP Proxies with username "veryspecial" and password "test]satellite@password+". The test connection for the configured proxy was successful, with the following message in the proxy log: 1629278218.735 1745 10.40.208.9 TCP_TUNNEL/200 1126560 CONNECT www.cnn.com:443 - HIER_DIRECT/199.232.93.67 - - set the proxy configured in the previous step as the default one in Administer -> Settings -> Content -> Default HTTP Proxy - import a new manifest - enable a few RPM and Kickstart repositories in Content -> Red Hat Repositories - successfully sync repos enabled in the previous step, with a lot of TCP_TUNNEL/200 messages in the proxy access.log
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory (Moderate: Satellite 6.10 Release), and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2021:4702