When using suspending async/await, stacktrace contains no application code

Can be reproduced by simple test:

  @Test fun await404() {
    val retrofit = Retrofit.Builder()
            .baseUrl(server.url("/"))
            .addConverterFactory(ToStringConverterFactory())
            .build()
    val example = retrofit.create(Service::class.java)

    server.enqueue(MockResponse().setResponseCode(404))

    try {
      runBlocking {
        val deferred = async { example.body()  }

        deferred.await()
      }
      fail()
    } catch (e: HttpException) {
      val writer = StringWriter()
      e.printStackTrace(PrintWriter(writer))

      val trace = writer.toString()

      assertThat("KotlinSuspendTest" in trace).isTrue()
      assertThat("await404" in trace).isTrue()
    }
  }

By default the stacktrace will look like:

retrofit2.HttpException: HTTP 404 Client Error
	at retrofit2.KotlinExtensions$await$2$2.onResponse(KotlinExtensions.kt:53)
	at retrofit2.OkHttpCall$1.onResponse(OkHttpCall.java:161)
	at okhttp3.RealCall$AsyncCall.execute(RealCall.java:174)
	at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

This is not very helpful, as we don’t know which call caused the exception.

Attempt at fixing can be found in https://github.com/square/retrofit/pull/3475, comments appreciated. That would lead to following trace:

retrofit2.HttpException: HTTP 404 Client Error
	(Coroutine boundary)
	at retrofit2.KotlinSuspendTest$await404$1$deferred$1.invokeSuspend(KotlinSuspendTest.kt:190)
Caused by: retrofit2.HttpException: HTTP 404 Client Error
	at retrofit2.KotlinExtensions$await$2$2.onResponse(KotlinExtensions.kt:53)
	at retrofit2.OkHttpCall$1.onResponse(OkHttpCall.java:161)
	at okhttp3.RealCall$AsyncCall.execute(RealCall.java:174)
	at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

[nordfalk]

Yes @Red7M , you can surround all calls to retrofit in try/catch blocks. And then you invoke wrapToBeTraceable() to get the real stack trace: Like

            try {
                ... some call to retrofit
            } catch (notUseFullExteption: Exception) {
                val useFullExteption = Logger.wrapToBeTraceable(notUseFullExteption) 
                useFullExteption.printStackTrace()  // or whatever logging
            }

its ugly but the only way I can see to get at least some useful information.

[GiridharaSPK]

I have added wrong headers that caused me that HTTP 400 Bad request error.

removing the following worked .addHeader(“Content-Encoding”, “UTF-8”) .header(“Accept-Encoding”, “identity”)

  might help someone