Mint Adapter is failing to handle the :server_closed_request error reason

[igorrfc]

Hi everyone! My error tracker has been alerting about this error multiple times lately:

FunctionClauseError: no function clause matching in anonymous fn/2 in Tesla.Adapter.Mint.reduce_responses/3
  File "lib/tesla/adapter/mint.ex", line 328, in anonymous fn/2 in Tesla.Adapter.Mint.reduce_responses/3
  File "lib/enum.ex", line 2468, in Enum."-reduce/3-lists^foldl/2-0-"/3
  File "lib/tesla/adapter/mint.ex", line 298, in Tesla.Adapter.Mint.receive_packet/4
  File "lib/tesla/adapter/mint.ex", line 258, in Tesla.Adapter.Mint.receive_responses/4
  File "lib/tesla/adapter/mint.ex", line 197, in Tesla.Adapter.Mint.format_response/3
  File "lib/tesla/adapter/mint.ex", line 59, in Tesla.Adapter.Mint.call/2
  File "lib/tesla/middleware/retry.ex", line 88, in Tesla.Middleware.Retry.retry/3
  File "timer.erl", line 266, in :timer.tc/3

As you can see, there is no clear information about which request exactly this error is happening, thus I can't provide a way to reproduce it. I have the arguments being passed to the reduce_responses/3 fn though:

The first one is:

{:error, #Reference<0.4006778225.3585081345.246352>, %Mint.HTTPError{reason: {:server_closed_request, :internal_error}, module: Mint.HTTP2}}

And the second apparently is the API response containing (on map format) containing a data attribute.

Any thoughts about what could be the issue there? Thanks and let me know if I can provide more information or help :D

[yordis]

Are you in the latest version of Tesla and Mint? I will suggest verifying this is still an issue in the latest version.

It will be tricky without being able to reproduce thou.

It seems that https://github.com/elixir-tesla/tesla/blob/master/lib/tesla/adapter/mint.ex#L329-L341 may not match anybody of fn

Based on

{:error, #Reference<0.4006778225.3585081345.246352>, %Mint.HTTPError{reason: {:server_closed_request, :internal_error}, module: Mint.HTTP2}}

There is no matching for {:error ...}, so it would not work.

I am unsure if the issue is Mint Adapter or Mint Adapter combined with the Retry middleware and whatnot.

I will suggest trying to replicate it. It is hard to tell what to do and why this is happening.

Based on the error message :internal_errorspawning up some server that returns some 500s, it should hopefully work. At least, I would try that.