diff --git a/core/java/android/content/pm/PackageParser.java b/core/java/android/content/pm/PackageParser.java
index 04777baf13943..be41a7cf200c6 100644
--- a/core/java/android/content/pm/PackageParser.java
+++ b/core/java/android/content/pm/PackageParser.java
@@ -3083,9 +3083,6 @@ public class PackageParser {
             a.info.maxRecents = sa.getInt(
                     R.styleable.AndroidManifestActivity_maxRecents,
                     ActivityManager.getDefaultAppRecentsLimitStatic());
-            a.info.screenOrientation = sa.getInt(
-                    R.styleable.AndroidManifestActivity_screenOrientation,
-                    ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
             a.info.configChanges = sa.getInt(R.styleable.AndroidManifestActivity_configChanges, 0);
             a.info.softInputMode = sa.getInt(
                     R.styleable.AndroidManifestActivity_windowSoftInputMode, 0);
@@ -3113,6 +3110,14 @@ public class PackageParser {
             a.info.resizeable = sa.getBoolean(
                     R.styleable.AndroidManifestActivity_resizeableActivity,
                     owner.applicationInfo.targetSdkVersion >= Build.VERSION_CODES.MNC);
+            if (a.info.resizeable) {
+                // Fixed screen orientation isn't supported with resizeable activities.
+                a.info.screenOrientation = ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED;
+            } else {
+                a.info.screenOrientation = sa.getInt(
+                        R.styleable.AndroidManifestActivity_screenOrientation,
+                        ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
+            }
         } else {
             a.info.launchMode = ActivityInfo.LAUNCH_MULTIPLE;
             a.info.configChanges = 0;
diff --git a/core/res/res/values/attrs_manifest.xml b/core/res/res/values/attrs_manifest.xml
index 84609cadaf140..1849b5c14f9ef 100644
--- a/core/res/res/values/attrs_manifest.xml
+++ b/core/res/res/values/attrs_manifest.xml
@@ -1023,7 +1023,11 @@
          <p>NOTE: A task's root activity value is applied to all additional activities launched in
          the task. That is if the root activity of a task is resizeable then the system will treat
          all other activities in the task as resizeable and will not if the root activity isn't
-         resizeable. -->
+         resizeable.
+
+         <p>NOTE: The value of {@link android.R.attr#screenOrientation} will be ignored for
+         resizeable activities as the system doesn't store fixed orientation on a resizeable
+         activity. -->
     <attr name="resizeableActivity" format="boolean" />
 
     <!-- The <code>manifest</code> tag is the root of an
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index 7a493c6d0e3bd..8ef99e1d77b9b 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -3731,6 +3731,10 @@ public final class ActivityManagerService extends ActivityManagerNative
             if (r == null) {
                 return;
             }
+            if (r.task != null && r.task.mResizeable) {
+                // Fixed screen orientation isn't supported with resizeable activities.
+                return;
+            }
             final long origId = Binder.clearCallingIdentity();
             mWindowManager.setAppOrientation(r.appToken, requestedOrientation);
             Configuration config = mWindowManager.updateOrientationFromAppTokens(
diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index 3cf3eb7dbb7ff..4d7305d5a9884 100644
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -3730,10 +3730,19 @@ final class ActivityStack {
         // we just want to leave the official config object now in the
         // activity and do nothing else.
         int stackChanges = oldStackOverride.diff(mOverrideConfig);
-        if (stackChanges == 0 && !oldStackOverride.equals(mOverrideConfig)) {
-            // Assume size change if diff didn't report any changes,
-            // but configurations are not equal.
-            stackChanges = ActivityInfo.CONFIG_SCREEN_SIZE;
+        if (stackChanges == 0) {
+            // {@link Configuration#diff} doesn't catch changes from unset values.
+            // Check for changes we care about.
+            if (oldStackOverride.orientation != mOverrideConfig.orientation) {
+                stackChanges |= ActivityInfo.CONFIG_ORIENTATION;
+            }
+            if (oldStackOverride.screenHeightDp != mOverrideConfig.screenHeightDp
+                    || oldStackOverride.screenWidthDp != mOverrideConfig.screenWidthDp) {
+                stackChanges |= ActivityInfo.CONFIG_SCREEN_SIZE;
+            }
+            if (oldStackOverride.smallestScreenWidthDp != mOverrideConfig.smallestScreenWidthDp) {
+                stackChanges |= ActivityInfo.CONFIG_SMALLEST_SCREEN_SIZE;
+            }
         }
         final int changes = oldConfig.diff(newConfig) | stackChanges;
         if (changes == 0 && !r.forceNewConfig) {
diff --git a/services/core/java/com/android/server/wm/TaskStack.java b/services/core/java/com/android/server/wm/TaskStack.java
index 1c9dfe0ca5968..c677e2c5d9b65 100644
--- a/services/core/java/com/android/server/wm/TaskStack.java
+++ b/services/core/java/com/android/server/wm/TaskStack.java
@@ -185,6 +185,9 @@ public class TaskStack {
                 Math.min((int)(mBounds.height() / density), serviceConfig.screenHeightDp);
         mOverrideConfig.smallestScreenWidthDp =
                 Math.min(mOverrideConfig.screenWidthDp, mOverrideConfig.screenHeightDp);
+        mOverrideConfig.orientation =
+                (mOverrideConfig.screenWidthDp <= mOverrideConfig.screenHeightDp)
+                        ? Configuration.ORIENTATION_PORTRAIT : Configuration.ORIENTATION_LANDSCAPE;
     }
 
     void updateDisplayInfo() {