Android error: Expected to run on UI thread!

[AMBE1203]

• "react-native-view-shot": "3.5.0"
• "react-native": "0.71.4",

On Android, i have error: Expected to run on UI thread!

[shotforsky]

We successfuly generated an image, but there is this error, too. What does this mean and how could we bypass it?
We are using:

• "react-native-view-shot": "3.7.0"
• "react-native": "0.68.2"

Thanks in advance!

[caiotoledo-lunasystems]

I have the same error message on:

• "react-native-view-shot": "3.7.0"
• "react-native": 0.74.1

[wfern]

In my case even though the error is displayed the image is generated successfully because the "error" is only a assert that shows in debug mode: https://github.com/facebook/react-native/blob/9afad527b831ec0c5d50e88daacbaacbc476d478/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/fabric/FabricUIManager.java#L925

The warning is caused because the ui manager "view resolver" is called in another thread but it should be in the UI thread, since the ViewShot class implements UIBlock and is dispatched to the UI manager queue we only need to move the "view resolver" out of the background thread.

I made this patch to fix the issue:

diff --git a/node_modules/react-native-view-shot/android/src/main/java/fr/greweb/reactnativeviewshot/ViewShot.java b/node_modules/react-native-view-shot/android/src/main/java/fr/greweb/reactnativeviewshot/ViewShot.java
index ce81dda..7b7332b 100644
--- a/node_modules/react-native-view-shot/android/src/main/java/fr/greweb/reactnativeviewshot/ViewShot.java
+++ b/node_modules/react-native-view-shot/android/src/main/java/fr/greweb/reactnativeviewshot/ViewShot.java
@@ -195,26 +195,26 @@ public class ViewShot implements UIBlock, com.facebook.react.fabric.interop.UIBl
 
     //region Implementation
     private void executeImpl(final NativeViewHierarchyManager nativeViewHierarchyManager, final UIBlockViewResolver uiBlockViewResolver) {
+        final View view;
+
+        if (tag == -1) {
+            view = currentActivity.getWindow().getDecorView().findViewById(android.R.id.content);
+        } else if (uiBlockViewResolver != null) {
+            view = uiBlockViewResolver.resolveView(tag);
+        } else {
+            view = nativeViewHierarchyManager.resolveView(tag);
+        }
+
+        if (view == null) {
+            Log.e(TAG, "No view found with reactTag: " + tag, new AssertionError());
+            promise.reject(ERROR_UNABLE_TO_SNAPSHOT, "No view found with reactTag: " + tag);
+            return;
+        }
+
         executor.execute(new Runnable () {
             @Override
             public void run() {
                 try {
-                    final View view;
-
-                    if (tag == -1) {
-                        view = currentActivity.getWindow().getDecorView().findViewById(android.R.id.content);
-                    } else if (uiBlockViewResolver != null) {
-                        view = uiBlockViewResolver.resolveView(tag);
-                    } else {
-                        view = nativeViewHierarchyManager.resolveView(tag);
-                    }
-
-                    if (view == null) {
-                        Log.e(TAG, "No view found with reactTag: " + tag, new AssertionError());
-                        promise.reject(ERROR_UNABLE_TO_SNAPSHOT, "No view found with reactTag: " + tag);
-                        return;
-                    }
-
                     final ReusableByteArrayOutputStream stream = new ReusableByteArrayOutputStream(outputBuffer);
                     stream.setSize(proposeSize(view));
                     outputBuffer = stream.innerBuffer();

[The-Gopher]

Had the same issue and this fix didn't solve it for me. This did:

diff --git a/node_modules/react-native-view-shot/android/src/main/java/fr/greweb/reactnativeviewshot/ViewShot.java b/node_modules/react-native-view-shot/android/src/main/java/fr/greweb/reactnativeviewshot/ViewShot.java
index ce81dda..5a13006 100644
--- a/node_modules/react-native-view-shot/android/src/main/java/fr/greweb/reactnativeviewshot/ViewShot.java
+++ b/node_modules/react-native-view-shot/android/src/main/java/fr/greweb/reactnativeviewshot/ViewShot.java
@@ -195,7 +195,9 @@ public class ViewShot implements UIBlock, com.facebook.react.fabric.interop.UIBl

     //region Implementation
     private void executeImpl(final NativeViewHierarchyManager nativeViewHierarchyManager, final UIBlockViewResolver uiBlockViewResolver) {
-        executor.execute(new Runnable () {
+        Handler mainHandler = new Handler(this.currentActivity.getMainLooper());
+
+        mainHandler.post(new Runnable () {
             @Override
             public void run() {
                 try {