FunctionWrappers.jl -> ERROR: LoadError: TypeError: in cfunction, expected Union{}, got a value of type Nothing

The more I investigated this error, the more confused I got. It’s to the point where I don’t even think I could give an accurate reproduction procedure.

All I know and all I want to share with people that search for this error message is that restarting Julia fixed the issue. This is the same solution that worked for a similar question.

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Sorry, this is going to be very difficult if you cannot provide a reproducer.

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I don’t need help. I only made this post to suggest to people facing similar issues to try restarting Julia.

If someone figures out what causes this (I suspect some Revise edge case, but I really shouldn’t speculate like that), then they should feel free to comment, but no need.

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LOL! I had the issue again, so I copy pasted the error message into Google search and lo and behold, it brought me back to this post I had completely forgotten about.

The best part is that the solution was indeed to restart Julia! Sorry to necro the thread, but this was too funny not to share.

Thanks for sharing. I encountered this problem today and fixed it by restarting julia. The error appears when I am using DifferentialEquations.jl. So, it’s probably related to this issue, Functions do not properly redefine with FunctionWrappers in v1.10? · Issue #52635 · JuliaLang/julia