Resolving 'Invalid Proxy Invocation' in Elixir

Invalid Proxy Invocation in Elixir is a relatively uncommon runtime error that occurs when interacting with proxies or dynamically-generated modules in metaprogramming-heavy applications.

It typically happens when using libraries like Plug or Phoenix with middleware that improperly wraps function calls.

Start by examining the proxy invocation context.

If you’re using Plug, check your pipeline definitions in router.ex to ensure middleware modules are correctly referenced.

For instance, replacing plug :some_middleware with plug SomeMiddleware is a common fix.

Misaligned module configurations can also cause this error, especially when using dynamic module generation (Module.create) without proper function export.

Always define the __proxy__/2 function when building proxies manually, as this is expected during invocation.

If the error persists, it might be due to improper handling of metaprogrammed functions.

Verify that all dynamic modules implement the apply/3 function properly.

Use IO.inspect/2 to trace where the proxy breaks and adjust accordingly.

Testing your modules in isolation can help identify specific issues with middleware or proxies.

Resolving this error ensures smoother runtime behavior in complex Elixir applications.