Fail to load workflow from png saved with some custom nodes.

[49RpK5dY]

Dragging or directly opening images saved with some custom nodes fails to load embedded workflow on 1.32.1.

test.saver.json

Tested https://github.com/wallish77/wlsh_nodes and https://github.com/alexopus/ComfyUI-Image-Saver
Trying to open first saved image results in new workflow but it is just a copy of the one that was already open. The second one builds a new workflow from scratch based on metadata instead of opening embedded workflow. Third one works as intended.

Dragging images saved on 1.32.1 in 1.32.0 work just fine.

┆Issue is synchronized with this Notion page by Unito

[dosubot]

This is a known issue in ComfyUI v1.32.1 caused by a file handling refactor that changed how workflow metadata is parsed from PNGs. If the backend inserts a NaN value (for example, in the is_changed field when an exception occurs), the resulting PNG metadata contains invalid JSON. The new frontend logic tries to eagerly parse both the workflow and prompt JSON, so if either contains invalid JSON (like a literal NaN), loading fails—even if the workflow itself is valid. This matches your symptoms and only affects v1.32.1; v1.32.0 does not have this problem because it used lazy parsing and would skip the invalid prompt if a valid workflow was present.

There are related issues and a detailed explanation here: GitHub Issue #4199.

Workarounds and next steps:

• The problematic refactor was reverted after reports, so updating to a newer version (after v1.32.1) should resolve the issue if the revert has been released.
• If you must use v1.32.1, you can try manually sanitizing the PNG metadata to remove NaN values, but this is tedious.
• For plugin authors: ensure custom nodes do not emit NaN in metadata, or patch the backend to use null/None instead of NaN for error states.

More details and technical background are in the linked issue.

To reply, just mention @dosu.

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