ah. so earlier in the log, I see this:

## We're checking if /opt/puppetlabs/server/data/staging/pe_repo-puppet-agent-8.20.0/puppet-enterprise-2025.11.2-el-9-x86_64/conf.d/custom-pe.conf contains valid HOCON syntax...

2026-08-27T21:09:31.367+00:00 Running command: /opt/puppetlabs/installer/bin/validate_pe_conf.rb /opt/puppetlabs/server/data/staging/pe_repo-puppet-agent-8.20.0/puppet-enterprise-2025.11.2-el-9-x86_64/conf.d/custom-pe.conf
./puppet-enterprise-installer: line 665: /opt/puppetlabs/installer/bin/validate_pe_conf.rb: No such file or directory
2026-08-27T21:09:31.382+00:00 [ERROR]: !! Validation failure. !!
Rolling puppet-agent back to 8.20.0.
Rolling pe-installer back to PE 2025.11.0.
Rolling pe-modules back to PE 2025.11.0.

something missing from the installer build?

I cannot reproduce this, do you have more of that install log?

We have an open support case # 01623710 and we put the output in there.

I had a look at the full log and understand what happened now and have passed that along to support.

awesome, thanks!