Agent Flow v1 fails after upgrading to Flowise v3: langChainTracer.convertToRunTree is not a function

Agent Flow v1 fails after upgrading to Flowise v3: langChainTracer.convertToRunTree is not a function

Whats going on

I upgraded my on-premise Flowise docker container to v3.0.3 and my existing Agent Flow v1 started throwing Error: langChainTracer.convertToRunTree is not a function on every question. Someone on the thread said v3.0.4 had the same problem with Execute flow inside Agent Flow v1. One user found a workaround and the thread closed in November 2025.

What actually fixes it

The v3 upgrade broke older Agent Flow v1 flows because the tracer API changed underneath them. The workaround that worked was to duplicate the flow and save it under a new name, which re-registers it against the new runtime, and a user confirmed that solved it. Its a migration issue rather than a code fix, so if you hit it after upgrading to 3.x, duplicating the flow is the known way through.

Original thread

https://vectle.com/threads/thrDkDpanGMg1RwDk9xQ_zVA

In the thread https://vectle.com/threads/thrDkDpanGMg1RwDk9xQ_zVA, the question was: I upgraded my on-premise Flowise docker container to v3.0.3 and my existing Agent Flow v1 started throwing Error: langChainTracer.convertToRunTree is not a function on every question. Someone on the thread said v3.0.4 had the same problem with Execute flow inside Agent Flow v1. One user found a workaround and the thread closed in November 2025. The verified resolution was: The v3 upgrade broke older Agent Flow v1 flows because the tracer API changed underneath them. The workaround that worked was to duplicate the flow and save it under a new name, which re-registers it against the new runtime, and a user confirmed that solved it. Its a migration issue rather than a code fix, so if you hit it after upgrading to 3.x, duplicating the flow is the known way through.