"WARNING: no connection to server" errors on webserver startup #42
Description
During the application startup, there are instances of the following error in weblog.log:
2025-08-19 16:20:34.862 visDQMRenderLink[2310/139782349313792]: WARNING: no connection to server #8
[19/Aug/2025:16:20:34] WARNING: unable to produce a plot: cannot convert 'NoneType' object to bytes ~~ Traceback (most recent call last): ~~ File "/data/srv/HG2501a/sw/venv/lib/python3.8/site-packages/Monitoring/Core/GUI.py", line 711, in plotfairy ~\
~ (type, data) = s.plot(*args[1:], **kwargs) ~~ File "/data/srv/HG2501a/sw/venv/lib/python3.8/site-packages/Monitoring/DQM/GUI.py", line 648, in plot ~~ return (a[0], bytes(a[1])) ~~ TypeError: cannot convert 'NoneType' object to bytes ~~
[19/Aug/2025:16:20:34] vocms0737.cern.ch 46.34.230.243:13242 "GET /dqm/relval/plotfairy/overlay?session=xy81na31;v=1755053702934636891;ref=ratiooverlay;obj=archive%2F394959%2FZeroBias%2FCMSSW_15_0_10-HLTNew_TkAl_RelVal-v3%2FDQMIO%2FHLT%2FTracking%2Fpixe\
lTracks%2FGeneralProperties%2FTrackPzErrOverPz_ImpactPoint_GenTk;obj=archive%2F394959%2FZeroBias%2FCMSSW_15_0_10-HLTRef_TkAl_RelVal-v3%2FDQMIO%2FHLT%2FTracking%2FpixelTracks%2FGeneralProperties%2FTrackPzErrOverPz_ImpactPoint_GenTk;reflabel=Reference;nor\
m=False;w=266;h=200 HTTP/1.1" 200 [data: - in 974 out 3250797 us ] [auth: ok "/DC=ch/DC=cern/OU=Organic Units ] [ref: "https://cmsweb.cern.ch" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100\
101 Firefox/113.0" ]
This is transient, and goes away after a few seconds.