You may come across this error if you are ever trying to create an Android build for the Google Play store. This error occurs if you are trying to make a 64-bit architecture build of your game and you are using the wrong version of the Android NDK. This error is also more common because Google will now be requiring your APK in both 32 and 64-bit. This will require you to switch the scripting backend from Mono to IL2CPP and then you have to select the different architecture you want to build for and this is when this error occurs but this error only occurs when you try to build your project. To fix this error you need to download an older version of the Android NDK. The version you need is Android NDK r16b and here is the link to download it. You then have to set the address of you NDK in the External tools of Unity. After doing this The errors should be gone and you should now be able to create a 64-bit APK of your game in Unity.
Documentation:
https://forum.unity.com/threads/googleplay-64bit-console-warning.672988/
https://forum.unity.com/threads/2019-1-10f1-wont-build-to-android-device.709610/
NDK: https://developer.android.com/ndk/downloads/older_releases.html
