Unable to create call adapter for retrofit2.Response<...>

Question

My Api:

@GET("/cinema/notShownMovies")
fun getNotShownMovies(
   @Query("token") token: String
): Response<GetMovieResponse>

Exception when trying to call API:

java.lang.IllegalArgumentException: Unable to create call adapter for retrofit2.Response<...data.GetMovieResponse> for method InstanceApi.getNotShownMovies Unable to create call adapter for retrofit2.Response<...data.GetMovieResponse> for method InstanceApi.getNotShownMovies

I don't know where to start. All other API calls work fine which is also defined in the same API class. Maybe a model error?

Your other methods that work in the service are wrapped in `Response<>` or `Call<>`? — Saurabh Thorat, Jun 19 '20 at 07:10
val retrofit = Retrofit.Builder() .client(client) .baseUrl(url) .addConverterFactory(MoshiConverterFactory.create()) .build() return retrofit.create(Api::class.java) — kaulex, Jun 19 '20 at 07:15

Abdul Mateen · Accepted Answer · 2020-06-19T07:42:54.550

54

Just add suspend modifier if using coroutines. This will solve the problem.

Otherwise your issue is likely because there is no Call adapter added when instantiating your Retrofit object. For example, for RxJava2, you can include a call adapter by adding this line while building it.

.addCallAdapterFactory(RxJava2CallAdapterFactory.createWithScheduler(Schedulers.io()))

edited Jun 19 '20 at 07:42

answered Jun 19 '20 at 07:28

Abdul Mateen

1,418
1
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32

I am using kotlin coroutines so why would I need RxJava? Furthermore, this does not explain why it is working on all other calls. – kaulex Jun 19 '20 at 07:29
8

If you're using coroutines, then include keyword `suspend` before your function. I also believe you simply need to wrap your data class in `Response`. – Abdul Mateen Jun 19 '20 at 07:34
2

Yeah this error message is not helpful at all in identifying a missing `suspend`. – Abdul Mateen Jun 19 '20 at 07:36
1

Missing the suspend for this API, thanks a lot. – Nguyen Mar 23 '21 at 06:41
2

Thanks a lot,,,,, I have tried full day, Its missing of *Suspend* for api function – Suhad Bin Zubair Nov 02 '21 at 16:23
2

@SuhadBinZubair I had the same issue missing suspend on the retrofit API call. Did that and it worked perfect. – JPM Feb 24 '22 at 15:15
Yeah it works great. I tried a lot and changed my retrofit implementation to enque method. – Jarin Rocks Mar 23 '22 at 18:10
Why does adding the suspend keyword fix it? They seem very unrelated...but if it does the trick... – Sam Nov 30 '22 at 15:47

score 12 · Answer 2 · answered Nov 25 '22 at 14:12

I had a similar crash IllegalArgumentException: Call return type must be parameterized as Call.

Crash log:

Caused by: java.lang.IllegalArgumentException: Unable to create call adapter for interface retrofit2.Call
    for method Api.login
    at retrofit2.Utils.methodError(Utils.java:54)
    at retrofit2.HttpServiceMethod.createCallAdapter(HttpServiceMethod.java:116)
    at retrofit2.HttpServiceMethod.parseAnnotations(HttpServiceMethod.java:67)
    at retrofit2.ServiceMethod.parseAnnotations(ServiceMethod.java:39)
    at retrofit2.Retrofit.loadServiceMethod(Retrofit.java:202)
    at retrofit2.Retrofit$1.invoke(Retrofit.java:160)
    at java.lang.reflect.Proxy.invoke(Proxy.java:1006)
    at $Proxy0.login(Unknown Source)
    at <redacted>.screen.login.LoginActivity.onSignInClick(LoginActivity.java:103)
    ... 13 more
Caused by: java.lang.IllegalArgumentException: Call return type must be parameterized as Call<Foo> or Call<? extends Foo>
    at retrofit2.DefaultCallAdapterFactory.get(DefaultCallAdapterFactory.java:42)
    at retrofit2.Retrofit.nextCallAdapter(Retrofit.java:253)
    at retrofit2.Retrofit.callAdapter(Retrofit.java:237)
    at retrofit2.HttpServiceMethod.createCallAdapter(HttpServiceMethod.java:114)
    ... 20 more

I found out it was crashing because of Proguard/R8. Proguard was renaming Retrofit classes and to fix it I updated the Proguard settings with:

-dontwarn retrofit2.**
-keep class retrofit2.** { *; }

It did solve the problem for crashing, but I am started facing problem adapters. For example I see same item getting displayed multiple times. — Arpit, Jun 23 '23 at 14:19
It solved :) When I updated my app last December than I haven't faced this issue that time. Today I need to add 2 Progard Rules. Don't know why? — M DEV, Jul 27 '23 at 15:58
@Arpit I get the same issue of items being displayed multiple times. How did you fix? — Dayem Saeed, Aug 08 '23 at 00:46
There are some proguard rules need to define for gson @DayemSaeed please check that — Arpit, Aug 10 '23 at 08:19
My `proguard-rules` file had retrofit rules but without the `2` and your comment saved my life Such a little detail brought me so much trouble... — Ícaro, Aug 29 '23 at 17:59

score -3 · Answer 3 · answered Sep 22 '22 at 05:30

-3

In the Gradle file add this line inside of release buildTyps

minifyEnabled false

answered Sep 22 '22 at 05:30

Hardik Patel

1
1

1

Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer). – abdo Salm Sep 26 '22 at 19:10

Unable to create call adapter for retrofit2.Response<...>

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