Jenkins 2.234, AWS ec2 instance running jenkins container.

Jenkins URL: https://jenkins-backend.dev.cicdenv.com/
Resoure Root URL: https://builds-backend.dev.cicdenv.com/

Both DNS names go to an AWS ALB with host routing rules.

jenkins:
crumbIssuer:
standard:
excludeClientIPFromCrumb: true

The server/resource root URLs are set in groovy hooky scripts:
JenkinsLocationConfiguration.get().url = ...
ResourceDomainConfiguration.get().url = ...

I haven't used a separate resource root url before.
https://github.com/jenkinsci/jenkins/pull/4239

I put a custom logo override into userContent and it is working which leads me to believe the resource root url setting is working, however the check against /instance-identity/ is failing in the configure page.

I don't think this problem is new in version 2.234.

I am able to reproduce it with a 2.234 docker image. Weird, I specifically tested this.

This worked as intended in 2.200.

This broke in 2.205 because of the Winstone update that changed the 404 error message format.

The form validation expects a message to occur in a 404 error response and it seems it no longer matches exactly. That's the only difference between the "404 Not Found" error, and "This is a previously set up resource domain".

Upstream regression is https://github.com/eclipse/jetty.project/issues/4154 (and rejected).

Just to confirm,

I put a custom logo override into userContent and it is working which leads me to believe the resource root url setting is working, however the check against /instance-identity/ is failing in the configure page.

This is correct; it's just the form validation that's affected, as it can no longer distinguish a 404 response from a resource root URL from just any other 404 response.

danielbeck - thanks for responding and diagnosing so quickly.