Update README.md

README.md

@@ -26,6 +26,7 @@ To get started with the demo apps, follow the instructions below:
 | 204           | Indicates that no ads are currently eligible for your device. |
 | -5001         | Indicates that the ad failed to load due to various reasons (such as no networks being able to fill). |
 | -5201         | Indicates an internal state error with the AppLovin MAX SDK. |
+| -5601         | Indicates the provided `Activity` instance has been garbage collected while the AppLovin MAX SDK attempts to re-load an expired ad. (Android only) |
 
 ## Support
 We recommend using GitHub to file issues. For feature requests, improvements, questions or any other integration issues using MAX Mediation by AppLovin, please reach out to your account team and copy [email protected].