Generate Signed APK - Error:java: invalid source release: 14

Recently I started with Flutter and made an app, now I am trying to sign the APK for the release version as documented in: https://developer.android.com/studio/publish/app-signing

I have searched a lot on the internet but I have absolutely no clue what I am doing wrong..

When I try to generate the signed APK with my Keystore I am running into an error:

• Information:java: Errors occurred while compiling module 'vista_presentie'
• Information:javac 1.8.0_242-release was used to compile java sources
• Information:Module "vista_presentie" was fully rebuilt due to project configuration/dependencies changes
• Information:28-10-2020 19:42 - Build completed with 1 error and 0 warnings in 5 s 852 ms

** Error:java: invalid source release: 14

If I need to give some more information from the code I will update this question as soon as possible, please just ask me :)

Kind Regards,

Kevin

It seems you're using Java 1.8 to compile but in your android studio project you may have set the java language level to 14.

In Android Studio, go to Project Structure -> Modules -> Properties and set Source Compatibility and Target Compatibility to 1.8 (Java 8)