(Retrofit) Could not locate converter for class crashing app

I was facing the same issue. I fixed it by adding :

compile 'com.squareup.retrofit2:converter-gson:<latest-version>'

to my build.gradle

Then specify the converter when creating my Retrofit instance.

Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(Constants.API_BASE_URL)
            .addConverterFactory(GsonConverterFactory.create())
            .build();

In Retrofit 2.0, Converter is not included in the package and when you are using Retrofit 2.0 Make Sure follow new URL pattern

Base URL: always ends with /

@Url: DO NOT start with /

Retrofit retrofit = new Retrofit.Builder()
        .baseUrl(Constants.API_BASE_URL)
        .addConverterFactory(GsonConverterFactory.create())
        .build();

For more information about 2.0 Follow this link Retrofit 2.0: The biggest update

And also update build.gradle.

implementation "com.squareup.retrofit2:converter-gson:$retrofit_version"

And add the extension in project level build.gradle file

ext {
retrofit_version= "2.x.x"
}

Change retrofit version accordingly

For me below dependency was there already

compile 'com.squareup.retrofit2:retrofit:2.0.2'

For gson 2.0.2 I changed

compile 'com.squareup.retrofit2:converter-gson:2.0.2'

Then add

Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(Constants.API_BASE_URL)
            .addConverterFactory(GsonConverterFactory.create())
            .build();

For Retrofit V2 add the following repositories -

compile 'com.squareup.retrofit2:retrofit:2.0.0'
compile 'com.google.code.gson:gson:2.6.2'
compile 'com.squareup.retrofit2:converter-gson:2.0.0'

Now use below code -

Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(API_URL)
            .addConverterFactory(GsonConverterFactory.create())
            .build();

Hope it will help :)

In the latest Retrofit 2.0,you should import the latest version :

compile 'com.squareup.retrofit2:retrofit:2.0.0'
compile 'com.squareup.retrofit2:converter-gson:2.0.0'
compile 'com.squareup.retrofit2:adapter-rxjava:2.0.0'

Be careful call baseUrl()，at v2.0,it should be end of "/",and at the method ,you would’t start thr url with"/"

@POST("classes/info")
Call<ContactBean> insertInfo(@Body ContactBean bean);

And you can see Retrofit to get more info! Hope help !