When upgrading to version 1.44 of the Junit plugin, I start getting the following Jenkins errors for most of my pipelines:

Downgrading to version 1.43 of the plugin resolves the issue.

If it matters, I'm using Nunit to run our tests and using the attached xslt to convert to the Junit format.  I don't think that's the issue, since it is giving the MissingFieldException for pipelines that don't run any tests as well.