xamarin, how to fix “dalvik.system.BaseDexClassLoader.findClass"

I am encountering this issue in the developer console, it works fine when I debug on my phone but when I install it on devices through the play store it just crash, and in the report, I get this error. what can I do to solve it?

java.lang.RuntimeException:

at android.app.ActivityThread.installProvider (ActivityThread.java:7905)

at android.app.ActivityThread.installContentProviders (ActivityThread.java:7441)

at android.app.ActivityThread.handleBindApplication (ActivityThread.java:7334)

at android.app.ActivityThread.access$2400 (ActivityThread.java:308)

at android.app.ActivityThread$H.handleMessage (ActivityThread.java:2295)

at android.os.Handler.dispatchMessage (Handler.java:110)

at android.os.Looper.loop (Looper.java:219)

at android.app.ActivityThread.main (ActivityThread.java:8347)

at java.lang.reflect.Method.invoke (Native Method)

at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:513)

at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1055)
Caused by: java.lang.ClassNotFoundException:

at dalvik.system.BaseDexClassLoader.findClass (BaseDexClassLoader.java:209)

at java.lang.ClassLoader.loadClass (ClassLoader.java:379)

at java.lang.ClassLoader.loadClass (ClassLoader.java:312)

at android.app.AppComponentFactory.instantiateProvider (AppComponentFactory.java:147)

at android.app.ActivityThread.installProvider (ActivityThread.java:7889)