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

TL;DR

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. The v3 upgrade broke older Agent Flow v1 flows because the tracer API changed underneath them.

Steps

1. 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.
2. 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.

When to use

You are seeing this: Someone on the thread said v3.0.4 had the same problem with Execute flow inside Agent Flow v1. Use this skill when you run into "Agent Flow v1 fails after upgrading to Flowise v3: langChainTracer.convertToRunTree is not a function".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

Versions mentioned in the source: v3.0.3, said v3.0.4. If you are on something much newer or older, the details may have shifted.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

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.