Issue with HIN pLHE request in central production

[lviliani]

Hello, we are having issues in producing events for this particular request in McM:
https://cms-pdmv-prod.web.cern.ch/mcm/requests?prepid=HIN-HINPbPbAutumn18pLHE-00106

It is a PbPb pLHE request and the corresponding campaign is using CMSSW_10_3_5.

The problem happens when producing events locally, so it will likely happen also in central production.
The requested events seem to be processed correctly, but at the end of the process we get the following fatal exception:

%MSG-e StateMachine:  PostGlobalEndRun 16-Oct-2025 14:46:31 CEST  PostGlobalEndRun
The EventProcessor state machine encountered an unexpected event
and went to the error state
Will attempt to terminate processing normally
(IF using the looper the next loop will be attempted)
This likely indicates a bug in an input module or corrupted input or both

%MSG
----- Begin Fatal Exception 16-Oct-2025 14:46:31 CEST-----------------------
An exception of category 'BadTransition' occurred while
   [0] Calling EventProcessor::runToCompletion (which does almost everything after beginJob and before endJob)
Exception Message:
Unexpected transition change 5
----- End Fatal Exception -------------------------------------------------

To reproduce this problem, you can log to lxplus8 or 9 and either download and execute directly the McM test script, or use the attached script, which is equivalent to the previous one but it runs on a smaller LHE file with only 100 events.

@DickyChant

HIN-HINPbPbAutumn18pLHE-00106.sh

[cmsbuild]

cms-bot internal usage

[cmsbuild]

A new Issue was created by @lviliani.

@Dr15Jones, @ftenchini, @makortel, @mandrenguyen, @sextonkennedy, @smuzaffar can you please review it and eventually sign/assign? Thanks.

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[makortel]

assign generators

The exception message indicates a problem with the Source, which I guess is LHESource in this case

[cmsbuild]

New categories assigned: generators

@lviliani,@mkirsano,@sensrcn,@theofil you have been requested to review this Pull request/Issue and eventually sign? Thanks

[lviliani]

@makortel right, in the attached script the source is:

process.source = cms.Source("LHESource",
    fileNames = cms.untracked.vstring('/store/lhe/20242/new_pythia_1.lhe')
)

[lviliani]

Let me add that I tried to use the same script but to run on different LHE files, in particular some that have been already produced in central production. And I got the same exception, which makes me think the problem is not related to the particular LHE file.