‘Execution failed for task ‘:tasks’. Could not create task ‘:react-native-bg-thread:compileDebugJavaWithJavac’.

In React Native, when setting up the simulator and its environment after installing a or every necessary dependency, the simulator might boot but would not run your application.

It then returns an en error:

'Execution failed for task ':tasks'.
> Could not create task ':react-native-bg-thread:compileDebugJavaWithJavac'.
> In order to compile Java 9+ source, please set compileSdkVersion to 30 or above'

to fix this, go to your project folder:

cd [projectname]

then

cd android

then find and open build.gradle.

Inside that file, add:

subprojects { subproject ->
    afterEvaluate{
        if((subproject.plugins.hasPlugin('android') || subproject.plugins.hasPlugin('android-library'))) {
            android {
                compileSdkVersion rootProject.ext.compileSdkVersion
                buildToolsVersion rootProject.ext.buildToolsVersion
            }
        }
    }
}

in your buildscript, just below the ext code block.

then rerun:

react-native run-android 

or whatever code that starts your simulator.

I hope this helps. Good luck ☘️.