Socket: set reusable port failed, error: Protocol not available(92),

I have a game with a version released on 2018.12.28 which used InAppPurchase. It worked. Now I open this project with newer version of Unity (2019.1.0f2), build it for Android, still works fine. But when I turn off the In-App-Purchase service and deactivate the InAppPurchase package, and delete the Plugins folder where those codes were, and then trying to to reenable the InAppPurchase and reactivate the InAppPurcahsePackage, Import the InAppPurchase code, when I build it and run it on Android phone, the logCat logs these errors on the game's startup (when the spash-screen is loading):

Socket: set reusable port failed, error: Protocol not available(92), see the log below:

 SystemInfo CPU = ARMv7 VFPv3 NEON, Cores = 4, Memory = 961mb
 SystemInfo ARM big.LITTLE configuration: 4 big (mask: 0xf), 0 little (mask: 0x0)
 ApplicationInfo com.funrob.fiar version 2018.12.28.2000n build 2d7539a5-1f92-422a-9925-250c3dfec025
 Built from '2019.1/staging' branch, Version '2019.1.0f2 (292b93d75a2c)', Build type 'Development', Scripting Backend 'mono', CPU 'armeabi-v7a', Stripping 'Disabled'
 Socket: set reusable port failed, error: Protocol not available(92)
  
 (Filename: ./Runtime/Network/Sockets.cpp Line: 415)
 Socket: set reusable port failed, error: Protocol not available(92)
  
 (Filename: ./Runtime/Network/Sockets.cpp Line: 415)
 Socket: set reusable port failed, error: Protocol not available(92)
  
 (Filename: ./Runtime/Network/Sockets.cpp Line: 415)
 Socket: set reusable port failed, error: Protocol not available(92)

And my game can't listen/receive the PlayStore callback, which should be come after purchasing a product or canceling purchasing.

The funny thing is, when I completely remove the IAP functionality from my game, these socket-reusable port exceptions are still coming at my game's startup (during the splash-screen-loading).

I did a text-search for this exception in my whole apk, and it is in apk\lib\armeabi-v7a\libunity.so What does this mean?!

Why it is still coming, even if I remove IAP from my game (all services are OFF in my project) How can I solve it, or is there a workaround? I spent a whole day trying to debug it, but no success. Any idea?