We recently upgraded from plugin v2.1.3 to v2.2.2.

Jobs which use the plugin to trigger remote builds WITHOUT parameters are failing and we get:

Server returned HTTP response code: 500 for URL: https://jenkinsurl/job/myJob123/buildWithParameters?delay=0
Connection to remote server failed, waiting for to retry - 10 seconds until next attempt.
Retry attempt #1 out of 5
Server returned HTTP response code: 500 for URL: https://jenkinsurl/job/myJob123/buildWithParameters?delay=0
Connection to remote server failed, waiting for to retry - 10 seconds until next attempt.
Retry attempt #2 out of 5
Server returned HTTP response code: 500 for URL: https://jenkinsurl/job/myJob123/buildWithParameters?delay=0
Connection to remote server failed, waiting for to retry - 10 seconds until next attempt.
Retry attempt #3 out of 5
Server returned HTTP response code: 500 for URL: https://jenkinsurl/job/myJob123/buildWithParameters?delay=0
Connection to remote server failed, waiting for to retry - 10 seconds until next attempt.
Retry attempt #4 out of 5
Server returned HTTP response code: 500 for URL: https://jenkinsurl/job/myJob123/buildWithParameters?delay=0
Connection to remote server failed, waiting for to retry - 10 seconds until next attempt.
Retry attempt #5 out of 5
Server returned HTTP response code: 500 for URL: https://jenkinsurl/job/myJob123/buildWithParameters?delay=0
ERROR: Remote build failed for the following reason:
ERROR: Max number of connection retries have been exeeded.

The URL seems to be incorrect as when we hit this target URL we see:

“You must use POST method to trigger builds. (From scripts you may instead pass a per-project authentication token, or authenticate with your API token.) If you see this page, it may be because a plugin offered a GET link; file a bug report for that plugin.”