Flow Execution Fails Due to Engine Version IncompatibilityIssue <!-- /*NS Branding Styles*/ --> .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } Flows remain stuck in "In Progress" state, preventing business operations from proceeding, if the MID Server version does not match the Instance version. Symptoms<!-- /*NS Branding Styles*/ --> .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } Error observed in MID Server logs: "Engine version is incompatible with context version after 5 retries".Issue may appear to be intermittent, and unlikely to be reproducible in lower environments. Release<!-- /*NS Branding Styles*/ --> .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } Seen in at least Xanadu and Zurich, so likely Any version. Cause<!-- /*NS Branding Styles*/ --> .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } A mismatch between application node version and instance/MID Server version causes the execution failures. That might be due to one of 2 possible reasons: One or more app nodes have not been upgraded, resulting in version incompatibility during flow execution. The intermittent behaviour is due to going wrong only on the appnodes that didn't upgrade, and it will be random which appnode is used.MID Servers Upgrading and Downgrading might also be seen in this situation, giving the false impression that the MID Server version being wrong is the cause. That is also just a side-effect, although may confuse the investigation. See: KB0697389 MID Servers repeatedly Upgrade and Downgrade between current and previous instance versionOne or more MID Servers hasn't upgraded itself to match the instance version. The MID Server agent log will confirm if this problem has happened. 2026-02-23T14:02:50.387-0500 DEBUG (Worker-Expedited:IPaaSActionProbe-<ecc_queue output sys_id>) [IHubRESTClient:80] Ihub Rest Client Http Status Code 409 : Error 1 : Method failed: (/api/now/hub/plan/<sys_flow_context sys_id>) with code: 4092026-02-23T14:02:50.387-0500 DEBUG (Worker-Expedited:IPaaSActionProbe-<ecc_queue output sys_id>) [IHubRESTClient:83] Ihub Rest Client Error making request. Retrying with new Cookie Cache...2026-02-23T14:02:50.519-0500 ERROR (Worker-Expedited:IPaaSActionProbe-<ecc_queue output sys_id>) [IntegrationHubMidChannelWrapper:152] Engine version is incompatible with context version after 5 retries.2026-02-23T14:02:50.519-0500 ERROR (Worker-Expedited:IPaaSActionProbe-<ecc_queue output sys_id>) [MidPFLogger:51] IPaaSActionProbe | Unable to retrieve plan due to following exception for context <sys_flow_context sys_id>com.snc.process_flow.exception.ProcessAutomationException: Failed transfer plan context: <sys_flow_context sys_id> to MID because there is a version incompatibilityat com.snc.process_flow.integration.MIDPAEnvironmentShifter.sendDataToInstance(MIDPAEnvironmentShifter.java:51)at com.snc.process_flow.integration.MIDPAEnvironmentShifter.shiftEnvironment(MIDPAEnvironmentShifter.java:29)at com.snc.process_flow.engine.MidProcessAutomation.shiftEnvironment(MidProcessAutomation.java:126)at com.snc.process_flow.engine.ProcessAutomation.runWithExecutionResult(ProcessAutomation.java:131)at com.snc.process_flow.engine.ProcessAutomation.run(ProcessAutomation.java:66)at com.snc.process_flow.engine.ProcessAutomation.resume(ProcessAutomation.java:62)at com.snc.process_flow.engine.MidProcessAutomation.resumeFlow(MidProcessAutomation.java:72)at com.service_now.mid.probe.IPaaSActionProbe.lambda$probe$0(IPaaSActionProbe.java:129)at com.glide.util.LogContext$Frame.run(LogContext.java:247)at com.service_now.mid.probe.IPaaSActionProbe.probe(IPaaSActionProbe.java:99) ... Comparing that with the instance appnode localhost log for the same request will confirm the appnode that fails is one of those that didn't upgrade. 2/23/26 2:02:50.517 PM 2026-02-23 11:02:50 (517) API_INT-thread-... ... txid=...tx_pattern_hash=2145011311 LocalhostTransactionLogger *** End #... /api/now/hub/plan/<sys_flow_context sys_id>, user: midserver, render_size: 0, total time: 0:00:00.006, processing time: 0:00:00.006, CPU time: 0:00:00.000, SQL time: 0:00:00.001 (count: 5), Total memory allocated: 1.53MB, source: x.x.x.x, type: rest, origin scope: global , method:PUT, api_name:now/hub, resource:now/hub/plan/{contextId}, version:Default, user_id:..., response_status:409 Resolution<!-- /*NS Branding Styles*/ --> .ns-kb-css-body-editor-container { p { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } span { font-size: 12pt; font-family: Lato; color: var(--now-color--text-primary, #000000); } h2 { font-size: 24pt; font-family: Lato; color: var(--now-color--text-primary, black); } h3 { font-size: 18pt; font-family: Lato; color: var(--now-color--text-primary, black); } h4 { font-size: 14pt; font-family: Lato; color: var(--now-color--text-primary, black); } a { font-size: 12pt; font-family: Lato; color: var(--now-color--link-primary, #00718F); } a:hover { font-size: 12pt; color: var(--now-color--link-primary, #024F69); } a:target { font-size: 12pt; color: var(--now-color--link-primary, #032D42); } a:visited { font-size: 12pt; color: var(--now-color--link-primary, #00718f); } ul { font-size: 12pt; font-family: Lato; } li { font-size: 12pt; font-family: Lato; } img { display: ; max-width: ; width: ; height: ; } } The affected node needs to be manually upgraded to the correct platform version. That is going to require a support case. Or, the MID Servers need to be allowed to upgrde themselves if that is the cause.Flows in "Waiting" status are nudged using scripts; flows in "In Progress" requires manual restart or cancellation and resubmission.The issue is mitigated using these steps. Note: PRB1860949 confirmed that the Flow engine is working as expected in this situtation, and just a symptom of the root cause, which is either why the appnode didn't upgrade, or why the MID Server didn't upgrade.