Many people when getting started with the Model Derivative API think that the name of the file uploaded to a bucket can just have any ID on its own, like "f789643d-bc65-4f32-8411-9a7c61f238b9"
However, the Model Derivative API relies on the file extension in order to determine which translator it should use. So the file name can be anything, but do not forget to keep the file extension.
Without that you'll get an HTTP 400 / Bad Request error with this message:
{"diagnostic":"Failed to trigger translation for this file."}
and x-ads-troubleshooting header saying:
"The system does not support this file format"