@abhishekdubey: I was experiencing the issue as well, when using the Native Maps-Plugin, the FCM-Plugin and the Background-Geolocation Plugin.
I was able to solve it, using @troovers guideline for FCM and Native Maps and adding one step (step 3) for the Background-Geolocation-Plugin.
What I did:
Step 1 (for FCM Plugin)
Comment out these lines in the FCMPlugin.gradle file.
classpath 'com.google.gms:google-services:3.0.0'
apply plugin: com.google.gms.googleservices.GoogleServicesPlugin
Step 2 (for FCM Plugin)
Change the plugin.xml of the FCM plugin to use a different version, in my situation 9.8.0.
<framework src="com.google.firebase:firebase-core:9.8.0" />
<framework src="com.google.firebase:firebase-messaging:9.8.0" />
Step 3 (for Background-Geolocation-Plugin)
Change the plugin.xml of the Geolocation plugin to use a different version, in my situation 9.8.0 instead of “+”.
<framework src="com.google.android.gms:play-services-location:9.8.0" />
Step 4
Remove and re-add plattform.
Step 5 (build.gradle file of the android platform folder)
Add this line to the classpath section
classpath 'com.google.gms:google-services:3.1.0'
And add this line below the dependencies, nearly at the bottom of the file
apply plugin: 'com.google.gms.google-services'