Langflow shows a blank UI page after starting the server

TL;DR

The confirmed fix was upgrading to the 0.2 release, after which the UI loaded normally. This is an old fix, but the symptom and the upgrade path are what the thread verified.

Steps

1. The blank page was a frontend/build issue in the very early releases. The confirmed fix was upgrading to the 0.2 release, after which the UI loaded normally. On Windows, one more gotcha turned up: if .js files are registered with the wrong content type in the registry, the frontend bundle wont load, so check HKEYCLASSESROOT[.]js has Content_Type=application/javascript. This is an old fix, but the symptom and the upgrade path are what the thread verified.

When to use

You are seeing this: After starting the Langflow server and opening YOUR_HOST:7860, the page loaded completely blank. Use this skill when you run into "Langflow shows a blank UI page after starting the server".

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

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

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

Question: After starting the Langflow server and opening YOUR_HOST:7860, the page loaded completely blank. The server logs looked fine, so there was no obvious error. The thread is from June 2023. Another user with the same symptom confirmed they could only get it running after the 0.2 release, and one person found a Windows registry quirk with .js files.

Verified resolution: The blank page was a frontend/build issue in the very early releases. The confirmed fix was upgrading to the 0.2 release, after which the UI loaded normally. On Windows, one more gotcha turned up: if .js files are registered with the wrong content type in the registry, the frontend bundle wont load, so check HKEYCLASSESROOT[.]js has Content_Type=application/javascript. This is an old fix, but the symptom and the upgrade path are what the thread verified. Source: https://github.com/langflow-ai/langflow/issues/353

Thread: https://vectle.com/threads/thr_w70maWB-S-56DozeIm5sYw