As you are trouble-shooting, immediately (very soon) after: The file hasn't been generated.
You are relating this past event to a current situation - needing the file.
In general (filling out the trouble-shooting report): The file wasn't generated.
(I don't know if "the process" is the thing that generates the file. If so, it would by "by the process." If some other part of the programming generates the file after "the process" has run, it would be "after the process.")
Note the file.
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