...
Resolution: is caused by having an incompatible app version for their SonarQube version. They need to upgrade the app to the latest version, that should resolve the issue.
5. Webhook set up failed
Check if you have a webhook configuration in SonarQube Admin -> Configuration -> Webhooks with the name ch.mibex.bitbucket.sonar:
...
If there is no webhook configuration for Bitbucket, please check the Bitbucket Server log for any errors. Also, check that your network/firewall configurations allow communication between SonarQube and Bitbucket.
If you have a webhook configuration, you should see Sonar annotations in your pull requests, after a new analysis has been run.
If no annotations are shown, please check the webhook delivery status in SonarQube under SonarQube Admin -> Configuration -> Webhooks. If you see a 502 Server Unreachable error, then it could be either that
you are using localhost or a wildcard address for Bitbucket which is not supported because SonarQube does not allow these. Please use the real Bitbucket hostname instead.
you do not have a valid HTTPS certificate for Bitbucket configured in SonarQube's JVM or you have proxy settings that prevent SonarQube from connecting Bitbucket. Please see this community article for more information.