Slack slash command can't hit my aws lambda endpoint

Question

I set up a the most basic aws lambda slash command handler. When I use try to use the slash command within slack. Slack responds with a error Darn - that slash command didn't work (error message: '400_client_error'). Manage the command at [name of my slash command]. After this I look into cloudwatch logs to see what error occurred and there is no trace of slack command.

I tried to hit the same endpoint with postman, and everything worked perfect (I even saw the logs in cloudwatch).

Answer 1

It took me a while to diagnose, but the problem had to do with transformations that were applied by API Gateway. The transformation that API Gateway was trying to apply would fail, and thus I would get a 400 error.