Issue

You receive lots of warnings in your logs with the following pattern:

WARNING: Found invalid crumb xxxxxxxxxxxxx. Will check remaining parameters for a valid one... 
hudson.security.csrf.CrumbFilter doFilter 
WARNING: No valid crumb was included in request for /ajaxExecutors. Returning 403.

Environment

CloudBees Jenkins Operations Center

Resolution

The issue is related to JENKINS-40344. This bug materializes in the logs if you have CSRF protection enabled (which is a recommended practise), to learn what is CSRF Protection, you can click here.

In the meantime, and as a workaround, you can avoid your logs to be flooded whith these messages by changing the log level to SEVERE on the following logger hudson.security.csrf.CrumbFilter.

In order to do this, please follow the procedure below:

• Navigate to Jenkins->Manage->System Log->Log Levels.
• Write hudson.security.csrf.CrumbFilter in the textbox, select the SEVERElevel value and then click submit.