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# Phoenix.MissingParamError exception (Phoenix v1.8.7)

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Raised when a key is expected to be present in the request parameters, but is not.

This exception is raised by `Phoenix.Controller.scrub_params/2` which:

- Checks to see if the required_key is present (can be empty)
- Changes all empty parameters to nils ("" -> nil)

If you are seeing this error, you should handle the error and surface it to the end user. It means that there is a parameter missing from the request.