When dealing with Unity, some errors may happen on specific versions or with specific configurations. So please share as many details as possible.

- Full Unity Version

- Scripting Runtime version, Scripting Backend & Api Compatability Level. All of them can be found on the Player Settings (Android tab).https://docs.unity3d.com/2018.2/Documentation/Manual/class-PlayerSettings.html

- OS (Windows or OSX, and their version)

- Android version, if the issue appears on the device itself

- Anything else that may be related

If possible, providing a demo project that reproduces the issue would greatly help and make it much easier for me to track down the issue and speed up the process.