Issue

I can see java.lang.ClassNotFoundException: org.apache.xerces.parsers.SAXParser errors in the logs and some plugin or functionality is not working on Jenkins.

Environment

• CloudBees Core
• CloudBees Core on modern cloud platforms - Managed Master
• CloudBees Core on modern cloud platforms - Operations Center
• CloudBees Core on traditional platforms - Client Master
• CloudBees Core on traditional platforms - Operations Center
• CloudBees Jenkins Enterprise
• CloudBees Jenkins Enterprise - Managed Master
• CloudBees Jenkins Enterprise - Operations Center
• CloudBees Jenkins Platform - Client Master
• CloudBees Jenkins Platform - Operations Center
• CloudBees Jenkins Distribution
• Jenkins LTS

Evidence

You are seeing a combination of the code below in your logs:

Caused: org.xml.sax.SAXException: SAX2 driver class org.apache.xerces.parsers.SAXParser not found
java.lang.ClassNotFoundException: org.apache.xerces.parsers.SAXParser

This means something changed the SAX driver, so any plugin that should use XML parsing could stop working correctly.

Workaround

A possible workaround to try solving this issue is adding the Java argument:

-Dorg.xml.sax.driver=com.sun.org.apache.xerces.internal.parsers.SAXParser

Tested product/plugin versions

Jenkins LTS 2.89.x

This issue should not be dependent of any Jenkins version though.