IssueTracker

check your v21 style, you might never extended the right parent which causes this issue.

@1 According to the docs and the error, I need to extend from the styles of the support library ("You need to use a Theme.AppCompat theme") , which is what I do. It worked before, so it should work fine now too.

My app uses a theme which extends Theme.AppCompat. It works with Proguard disabled but crashes when enabled. It's not just a problem with dinamically setting the theme.

@3 I see. I have no idea then what causes it, as when I try it on a new project it actually works fine.

My demo project depend on com.google.android.gms:play-services-analytics, with version 7.8.0, it works fine, with 8.1.0, this same problem occurs. I also have my app theme extend from Theme.AppCompat. The problem only occurs in release build. The behavior of the problem is the same with android support library version 23.0.1.

If it works with a clean project then it's not an Support Library issue. Over to Tor to see if it's a shrinkResources issue.

@6 I don't know who or what Tor is, but there is definitely a lot of compilation problems over the past new updates of all that's related to Google and Android.

@6 Here. I got to a sample that shows this issue.
Attached sample project. run on Android 2.3 emulator. it will crash with the same theme-exception.

password for the key file is "keykey".

I have the same problem :

java.lang.RuntimeException: Unable to start activity ComponentInfo{*}: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2107)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2132)
        at android.app.ActivityThread.access$700(ActivityThread.java:140)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1238)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4918)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
        at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
        at android.support.v7.app.t.a(AppCompatDelegateImplBase.java:124)
        at android.support.v7.app.AppCompatDelegateImplV7.a(AppCompatDelegateImplV7.java:146)
        at android.support.v7.app.q.onCreate(AppCompatActivity.java:59)

I might be wrong, but I think one of those fix it:

-dontwarn java.nio.file.Files
-dontwarn java.nio.file.Path
-dontwarn java.nio.file.OpenOption
-dontwarn org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement
 -keep class com.google.android.gms.** { *; }
 -dontwarn com.google.android.gms.**
 -keep class android.support.v7.** { *; }
 -keep interface android.support.v7.** { *; }
 -keep public class com.google.android.gms.**
 -dontwarn com.google.android.gms.**
 -keep class android.support.design.widget.** { *; }
 -keep interface android.support.design.widget.** { *; }
 -dontwarn android.support.design.**

This workaround works :

 -keep class com.google.android.gms.** { *; }
 -keep public class com.google.android.gms.**
 -dontwarn com.google.android.gms.**
 -keep class android.support.v7.** { *; }
 -keep interface android.support.v7.** { *; }

@11 I hope Google will put the needed proguard rules inside its own libraries, instead of us trying to find what can fix it.
It should also warn about not adding them, and have the error saying that it might be the cause for it.

@julien: It doesn't work for me. Do you put this in your proguard-rules.pro or in the default proguard-android.txt file? I have tried both, but it doesn't work :-(

@13 Try what I did on @11 . I think it works fine. You are supposed to put it in proguard-rules.pro 

@14: Done this already but the same error. Tried it in proguard-rules.pro and proguard-android.txt! Always the same error :-(

@14 Now it is working. Have cleaned up and retried. Works. Thanks.

@16 I think only a small part of what I wrote is needed. Maybe even just one line.

I got the above stacktrace only on release builds after updating my project to Play Services 8.1.  For me, turns out it was caused by the accidental inclusion of dependency on Admod by Google in Google Play Services 8.1:
https://plus.google.com/+GoogleDevelopers/posts/HsSNWEQ6H4e

You can exclude the 'play-services-ads' module in build.gradle (and update proguard rules) to fix this - see this SO answer for details:
http://stackoverflow.com/a/33375306/937715

@18: Ok, but it seems this is only if you are using Analytics.

Google Play Services 8.3 was released today. Has somebody testet it yet? Right now im using following in my proguard rules;

-keep class com.google.android.gms.** { *; }
-keep public class com.google.android.gms.**
-keep class android.support.v7.** { *; }
-keep interface android.support.v7.** { *; }
-dontwarn com.google.android.gms.**

and its working so far

@20 It actually got me into more issues. This time it claims a resource can't be found, even though it really does exist inside the project.
Then, I did a clean-project, and got this error:
Error:Execution failed for task ':app:packageRelease'.
> Unable to compute hash of D:\android\Android studio Projects\...\app\build\intermediates\classes-proguard\release\classes.jar

So I've deleted the build folder, and restarted Android-Studio, and then it deleted by itself the whole project, including all source files. I can't restore the files, and I've made a lot of changes since the last time...

Now I need to somehow remember what I did and restore it all.

I've succeeded restoring the app, but now when I generate a singed APK, I got this crash error at runtime :

11-06 19:58:18.438 28937-28937/com.lb.app_manager E/AndroidRuntime: FATAL EXCEPTION: main
                                                                    Process: com.lb.app_manager, PID: 28937
                                                                    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.lb..../com.lb.app_manager.activities.main_activity.MainActivity}: android.content.res.Resources$NotFoundException: File res/layout/abc_screen_simple_overlay_action_mode.xml from xml type layout resource ID #0x7f030014
                                                                        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2358)
                                                                        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2420)
                                                                        at android.app.ActivityThread.access$900(ActivityThread.java:154)
                                                                        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
                                                                        at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                        at android.os.Looper.loop(Looper.java:135)
                                                                        at android.app.ActivityThread.main(ActivityThread.java:5294)
                                                                        at java.lang.reflect.Method.invoke(Native Method)
                                                                        at java.lang.reflect.Method.invoke(Method.java:372)
                                                                        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
                                                                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
                                                                     Caused by: android.content.res.Resources$NotFoundException: File res/layout/abc_screen_simple_overlay_action_mode.xml from xml type layout resource ID #0x7f030014
                                                                        at android.content.res.Resources.loadXmlResourceParser(Resources.java:2843)
                                                                        at android.content.res.Resources.loadXmlResourceParser(Resources.java:2798)
                                                                        at android.content.res.Resources.getLayout(Resources.java:1143)
                                                                        at android.view.LayoutInflater.inflate(LayoutInflater.java:412)
                                                                        at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
                                                                        at android.support.v7.app.AppCompatDelegateImplV7.createSubDecor(SourceFile:381)
                                                                        at android.support.v7.app.AppCompatDelegateImplV7.ensureSubDecor(SourceFile:280)
                                                                        at android.support.v7.app.AppCompatDelegateImplV7.setContentView(SourceFile:254)
                                                                        at android.support.v7.app.AppCompatActivity.setContentView(SourceFile:109)
                                                                        at com.lb.app_manager.activities.main_activity.MainActivity.onCreate(SourceFile:48)
                                                                        at android.app.Activity.performCreate(Activity.java:5990)
                                                                        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
                                                                        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2311)
                                                                        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2420) 
                                                                        at android.app.ActivityThread.access$900(ActivityThread.java:154) 
                                                                        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321) 
                                                                        at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                        at android.os.Looper.loop(Looper.java:135) 
                                                                        at android.app.ActivityThread.main(ActivityThread.java:5294) 
                                                                        at java.lang.reflect.Method.invoke(Native Method) 
                                                                        at java.lang.reflect.Method.invoke(Method.java:372) 
                                                                        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904) 
                                                                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699) 
                                                                     Caused by: java.io.FileNotFoundException: res/layout/abc_screen_simple_overlay_action_mode.xml
                                                                        at android.content.res.AssetManager.openXmlAssetNative(Native Method)
                                                                        at android.content.res.AssetManager.openXmlBlockAsset(AssetManager.java:503)
                                                                        at android.content.res.Resources.loadXmlResourceParser(Resources.java:2825)
                                                                        at android.content.res.Resources.loadXmlResourceParser(Resources.java:2798) 
                                                                        at android.content.res.Resources.getLayout(Resources.java:1143) 
                                                                        at android.view.LayoutInflater.inflate(LayoutInflater.java:412) 
                                                                        at android.view.LayoutInflater.inflate(LayoutInflater.java:365) 
                                                                        at android.support.v7.app.AppCompatDelegateImplV7.createSubDecor(SourceFile:381) 
                                                                        at android.support.v7.app.AppCompatDelegateImplV7.ensureSubDecor(SourceFile:280) 
                                                                        at android.support.v7.app.AppCompatDelegateImplV7.setContentView(SourceFile:254) 
                                                                        at android.support.v7.app.AppCompatActivity.setContentView(SourceFile:109) 
                                                                        at com.lb.app_manager.activities.main_activity.MainActivity.onCreate(SourceFile:48) 
                                                                        at android.app.Activity.performCreate(Activity.java:5990) 
                                                                        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106) 
                                                                        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2311) 
                                                                        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2420) 
                                                                        at android.app.ActivityThread.access$900(ActivityThread.java:154) 
                                                                        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321) 
                                                                        at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                        at android.os.Looper.loop(Looper.java:135) 
                                                                        at android.app.ActivityThread.main(ActivityThread.java:5294) 
                                                                        at java.lang.reflect.Method.invoke(Native Method) 
                                                                        at java.lang.reflect.Method.invoke(Method.java:372) 
                                                                        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904) 
                                                                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699) 

Facing Same issue with ProGaurd

Thank you for your feedback. We assure you that we are doing our best to address the issue reported, however our product team has shifted work priority that doesn't include this issue. For now, we will be closing the issue as won't fix obsolete. If this issue currently still exists, we request that you log a new issue along with latest bug report here https://goo.gl/TbMiIO.