Retrofit 2.6.0 exception: java.lang.IllegalArgumentException: Unable to create call adapter for kotlinx.coroutines.Deferred

Question

I have a project with Kotlin coroutines and Retrofit.

I had these dependencies:

implementation 'com.squareup.retrofit2:retrofit:2.5.0'
implementation 'com.squareup.retrofit2:converter-gson:2.5.0'
implementation 'com.jakewharton.retrofit:retrofit2-kotlin-coroutines-adapter:0.9.2'

Today I have updated Retrofit to 2.6.0 in the project. In https://github.com/JakeWharton/retrofit2-kotlin-coroutines-adapter it is written that it is deprecated now. In https://github.com/square/retrofit/blob/master/CHANGELOG.md#version-260-2019-06-05 it is written that Retrofit currently supports suspend.

So, I removed retrofit2-kotlin-coroutines-adapter:0.9.2 and in Retrofit client changed these lines:

        retrofit = Retrofit.Builder()
            .baseUrl(SERVER_URL)
            .client(okHttpClient)
            .addConverterFactory(MyGsonFactory.create(gson))
            //.addCallAdapterFactory(CoroutineCallAdapterFactory()) - removed it.
            .build()

When run, the first request catches an exception:

java.lang.IllegalArgumentException: Unable to create call adapter for kotlinx.coroutines.Deferred<com.package.model.response.UserInfoResponse>
    for method Api.getUserInfo

As I understood, instead of CoroutineCallAdapterFactory() I could use CallAdapter.Factory(), but it is abstract.

If in Api class I change a request adding suspend in the beginning:

@FormUrlEncoded
@POST("user/info/")
suspend fun getUserInfo(@Field("token") token: String): Deferred<UserInfoResponse>

override suspend fun getUserInfo(token: String): Deferred<UserInfoResponse> =
    service.getUserInfo(token)

I get this exception:

java.lang.RuntimeException: Unable to invoke no-args constructor for kotlinx.coroutines.Deferred<com.package.model.response.UserInfoResponse>. Registering an InstanceCreator with Gson for this type may fix this problem.

CoolMind · Accepted Answer · 2019-08-02T08:27:39.190

35

Reading https://github.com/square/retrofit/blob/master/CHANGELOG.md#version-260-2019-06-05 I saw:

New: Support suspend modifier on functions for Kotlin! This allows you to express the asynchrony of HTTP requests in an idiomatic fashion for the language.

@GET("users/{id}") suspend fun user(@Path("id") long id): User

Behind the scenes this behaves as if defined as fun user(...): Call and then invoked with Call.enqueue. You can also return Response for access to the response metadata.

Currently this integration only supports non-null response body types. Follow issue 3075 for nullable type support.

I changed requests so: added suspend and removed Deferred:

@FormUrlEncoded
@POST("user/info/")
suspend fun getUserInfo(@Field("token") token: String): UserInfoResponse


override suspend fun getUserInfo(token: String): UserInfoResponse =
    service.getUserInfo(token)

Then in interactor (or simply when called the method getUserInfo(token)) removed await():

override suspend fun getUserInfo(token: String): UserInfoResponse =
    // api.getUserInfo(token).await() - was before.
    api.getUserInfo(token)

UPDATE

Once I encountered a situation when downloading PDF files required removing suspend in Api class. See How to download PDF file with Retrofit and Kotlin coroutines?.

edited Aug 02 '19 at 08:27

answered Jun 06 '19 at 08:45

CoolMind

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My answer was short and on point but your answer is complete with sources and everything. You can accept your own answer. – Eugen Pechanec Jun 06 '19 at 08:55
1

@EugenPechanec, nevertheless, you made a nice work and wasted time, and you were the first. At least, you deserve +10. – CoolMind Jun 06 '19 at 08:57
2

I don't do it for the points, it's fine. I appreciate your gesture. – Eugen Pechanec Jun 06 '19 at 09:00
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Thank you @CoolMind. You saved my bacon! – ninehundreds Feb 19 '21 at 02:48
@Eugen Pechanec Where is your answer? – The incredible Jan Jul 12 '21 at 08:47
@TheincredibleJan Hi, I deleted it because this answer is essentially the same but more complete. – Eugen Pechanec Jul 12 '21 at 08:51

Nicola Gallazzi · Answer 2 · 2019-07-02T13:32:31.237

16

In my case I was missing the CoroutineCallAdapterFactory in my Retrofit initialization. Retrofit v2.5.0

Before:

val retrofit = Retrofit.Builder()
                .baseUrl(BuildConfig.BASE_URL)
                .client(httpClient)
                .addConverterFactory(MoshiConverterFactory.create())
                .build()

After: (working code)

val retrofit = Retrofit.Builder()
                .baseUrl(BuildConfig.BASE_URL)
                .client(httpClient)
                .addConverterFactory(MoshiConverterFactory.create())
                .addCallAdapterFactory(CoroutineCallAdapterFactory())
                .build()

edited Jul 02 '19 at 13:32

answered Jul 02 '19 at 13:23

Nicola Gallazzi

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Well, what version of Retrofit do you use? – CoolMind Jul 02 '19 at 13:31
@CoolMind implementation 'com.squareup.retrofit2:retrofit:2.5.0' – Nicola Gallazzi Jul 02 '19 at 13:32
3

Ah, I see. Then, it makes sense. But I advise to upgrade to 2.6.0. Requests make simplier. – CoolMind Jul 02 '19 at 13:34
1

@CoolMind by the way in your question there's 2.5.0 version ;). In any case I just tested my code and it works for 2.6.0 version too – Nicola Gallazzi Jul 02 '19 at 13:39
2

Hah, I was upgrading from 2.5.0 to 2.6.0 and caught that exception. Currently it is Ok. Surprised that it works for 2.6.0. – CoolMind Jul 02 '19 at 13:40
Addition of Code .addCallAdapterFactory(CoroutineCallAdapterFactory()) helped – Supun Ayeshmantha Nov 03 '22 at 10:35

Retrofit 2.6.0 exception: java.lang.IllegalArgumentException: Unable to create call adapter for kotlinx.coroutines.Deferred

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