HTTP 413 "Request Entity Too Large" Troubleshooting in Windchill PDMLink

• How to troubleshoot Request Entity Too Large or Payload Too Large errors
• How to troubleshoot HTTP status code 413
• Users receiving intermittent Request Entity Too Large error when performing any action
• Users are getting an infinite loading screen when using the system
  • In some cases no error is displayed and a spinning wheel is shown
• Search issue with error Request Entity Too Large for multiple users
• Reproducible in Chrome, Firefox, Microsoft Edge
• While finishing task or creating a task, getting loading symbol in Windchill PDMLink
• While creating ECN, getting Request Entity too Large error
• Failed to upload attachment with error 'Request Entity Too Large' during creation of document 
• Users receiving intermittent HTTP 413 errors after configuring SSO with IBMid using OIDC
  • Disabling SSO allows Windchill to function normally
• Example of Chrome showing spinning wheel:

• The same operation in Edge failed immediately with the error message:

• HTTP/1.1 413 response in Apache access log:

xxx.xxx.xxx.xxx:51303 - <username> [03/Oct/2022:09:05:58 +0000] "POST /Windchill/ptc1/principalpicker/principalPickerCD_step?unique_page_number=58293595480137_0&AjaxEnabled=row&wizardActionClass=com.ptc.windchill.principal.administration.ParticipantCommands&wizardActionMethod=addPrincipalsToParticipantAdmin&tableID=table__participantAdministration.listParticipants_TABLE&actionName=addParticipantToPAList&portlet=poppedup&context=administration%24participantAdministration%24OR%3Awt.inf.container.OrgContainer%3A109160%24&oid=OR%3Awt.inf.container.OrgContainer%3A109160&stepId=principalpicker.principalPickerCD_step&dynamicStepLoad=true HTTP/1.1" 413 316 1175

• Apache mod_jk.log_XXXX-XX-XX_XX_XX_XX is reporting errors as the following:

[NO-ID] [3708756:140584756774656] [error] ajp_marshal_into_msgb::jk_ajp_common.c (520): (tomcat1) failed appending the query string of length 1151
--
[NO-ID] [3708756:140584681240320] [error] ajp_marshal_into_msgb::jk_ajp_common.c (476): (tomcat1) failed appending the header value for header 'cookie' of length 6
--
[NO-ID] [3985804:139724563912448] [error] ajp_get_reply::jk_ajp_common.c (2355): (tomcat1) Tomcat is down or refused connection. No response has been sent to the client (yet)
--
[NO-ID] [3985804:139724563912448] [error] ajp_service::jk_ajp_common.c (2933): (tomcat1) connecting to tomcat failed (rc=0, errors=2, client_errors=230).
--
[NO-ID] [2870914:139720696776448] [error] service::jk_lb_worker.c (1687): All tomcat instances failed, no more workers left
--
[NO-ID] [4149214:139647665547008] [error] ajp_get_reply::jk_ajp_common.c (2426): (tomcat1) Tomcat already send headers
--
[NO-ID] [4149214:139647665547008] [error] ajp_service::jk_ajp_common.c (2899): (tomcat1) sending request to tomcat failed (unrecoverable),  (attempt=1)
--
[NO-ID] [4149214:139647665547008] [error] service::jk_lb_worker.c (1627): unrecoverable error 502, request failed. Tomcat failed in the middle of request, we can't recover to another instance.

• Some of the Windchill pag