Android打包APK后请求接口报Unable to create call adapter for class t8.b for method a.a

Question

这到底是什么错啊，有的说retrofit2版本问题，我升级到2.9了还是会这样，我在AS编译到手机不会出现闪退，如果打包APK后请求网络接口就会闪退报错，如截图的日志，

 java.lang.IllegalArgumentException: Unable to create call adapter for class t8.b
                                                                                                        for method a.a
                                                                                                        at s9.k.r(Unknown Source:39)
                                                                                                        at db.s.b(Unknown Source:2696)
                                                                                                        at db.u0.b(Unknown Source:30)
                                                                                                        at db.t0.invoke(Unknown Source:44)
                                                                                                        at java.lang.reflect.Proxy.invoke(Proxy.java:1006)
                                                                                                        at $Proxy3.a(Unknown Source)
                                                                                                        at l6.a.m(Unknown Source:18)
                                                                                                        at d6.k.onClick(Unknown Source:155)
                                                                                                        at android.view.View.performClick(View.java:7616)
                                                                                                        at android.view.View.performClickInternal(View.java:7590)
                                                                                                        at android.view.View.access$3800(View.java:868)
                                                                                                        at android.view.View$PerformClick.run(View.java:29449)
                                                                                                        at android.os.Handler.handleCallback(Handler.java:955)
                                                                                                        at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                                                        at android.os.Looper.loopOnce(Looper.java:206)
                                                                                                        at android.os.Looper.loop(Looper.java:296)
                                                                                                        at android.app.ActivityThread.main(ActivityThread.java:9000)
                                                                                                        at java.lang.reflect.Method.invoke(Native Method)
                                                                                                        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:569)
                                                                                                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:976)
                                                                                                    Caused by: java.lang.IllegalStateException: Observable return type must be parameterized as Observable<Foo> or Observable<? extends Foo>
                                                                                                        at eb.h.a(Unknown Source:114)
                                                                                                        at db.u0.a(Unknown Source:32)
                                                                                                        at db.s.b(Unknown Source:2534)
                                                                                                        at db.u0.b(Unknown Source:30) 
                                                                                                        at db.t0.invoke(Unknown Source:44) 
                                                                                                        at java.lang.reflect.Proxy.invoke(Proxy.java:1006) 
                                                                                                        at $Proxy3.a(Unknown Source) 
                                                                                                        at l6.a.m(Unknown Source:18) 
                                                                                                        at d6.k.onClick(Unknown Source:155) 
                                                                                                        at android.view.View.performClick(View.java:7616) 
                                                                                                        at android.view.View.performClickInternal(View.java:7590) 
                                                                                                        at android.view.View.access$3800(View.java:868) 
                                                                                                        at android.view.View$PerformClick.run(View.java:29449) 
                                                                                                        at android.os.Handler.handleCallback(Handler.java:955) 
                                                                                                        at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                                                        at android.os.Looper.loopOnce(Looper.java:206) 
                                                                                                        at android.os.Looper.loop(Looper.java:296) 
                                                                                                        at android.app.ActivityThread.main(ActivityThread.java:9000) 
                                                                                                        at java.lang.reflect.Method.invoke(Native Method) 
                                                                                                        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:569) 
                                                                                                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:976) 

Answer 1

```java
java.lang.IllegalArgumentException: Unable to create call adapter for class t8.b
                                                                                                        for method a.a
                                                                                                        at s9.k.r(Unknown Source:39)
                                                                                                        at db.s.b(Unknown Source:2696)
                                                                                                        at db.u0.b(Unknown Source:30)
                                                                                                        at db.t0.invoke(Unknown Source:44)
                                                                                                        at java.lang.reflect.Proxy.invoke(Proxy.java:1006)
                                                                                                        at $Proxy3.a(Unknown Source)
                                                                                                        at l6.a.m(Unknown Source:18)
                                                                                                        at d6.k.onClick(Unknown Source:155)
                                                                                                        at android.view.View.performClick(View.java:7616)
                                                                                                        at android.view.View.performClickInternal(View.java:7590)
                                                                                                        at android.view.View.access$3800(View.java:868)
                                                                                                        at android.view.View$PerformClick.run(View.java:29449)
                                                                                                        at android.os.Handler.handleCallback(Handler.java:955)
                                                                                                        at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                                                        at android.os.Looper.loopOnce(Looper.java:206)
                                                                                                        at android.os.Looper.loop(Looper.java:296)
                                                                                                        at android.app.ActivityThread.main(ActivityThread.java:9000)
                                                                                                        at java.lang.reflect.Method.invoke(Native Method)
                                                                                                        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:569)
                                                                                                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:976)
                                                                                                    Caused by: java.lang.IllegalStateException: Observable return type must be parameterized as Observable<Foo> or Observable<? extends Foo>
                                                                                                        at eb.h.a(Unknown Source:114)
                                                                                                        at db.u0.a(Unknown Source:32)
                                                                                                        at db.s.b(Unknown Source:2534)
                                                                                                        at db.u0.b(Unknown Source:30) 
                                                                                                        at db.t0.invoke(Unknown Source:44) 
                                                                                                        at java.lang.reflect.Proxy.invoke(Proxy.java:1006) 
                                                                                                        at $Proxy3.a(Unknown Source) 
                                                                                                        at l6.a.m(Unknown Source:18) 
                                                                                                        at d6.k.onClick(Unknown Source:155) 
                                                                                                        at android.view.View.performClick(View.java:7616) 
                                                                                                        at android.view.View.performClickInternal(View.java:7590) 
                                                                                                        at android.view.View.access$3800(View.java:868) 
                                                                                                        at android.view.View$PerformClick.run(View.java:29449) 
                                                                                                        at android.os.Handler.handleCallback(Handler.java:955) 
                                                                                                        at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                                                        at android.os.Looper.loopOnce(Looper.java:206) 
                                                                                                        at android.os.Looper.loop(Looper.java:296) 
                                                                                                        at android.app.ActivityThread.main(ActivityThread.java:9000) 
                                                                                                        at java.lang.reflect.Method.invoke(Native Method) 
                                                                                                        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:569) 
                                                                                                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:976) 

```