I am working developing our custom application using this ref -link https://github.com/SiliconLabs/Bluegecko-android.
I have used demo application from sdk path F:\SimplicityStudio\v4\developer\sdks\gecko_sdk_suite\v1.1\app\bluetooth_2.4\appbuilder\sample-apps\soc-thermometer .
I have successfully done OTA on android version 7.0 and 8.0 but I am facing issue with android version 6.0 .
BLE successfully bootup in ota mode with android version-6.0 but i cannot able to write data on OTA characteristics,it showing me error "GATT INVALID handler".
That typically means that the characteristic handlers between the master and the slave for a given characteristic don't match.
Can you make sure the handler defined in your gatt_db.h matches the one in your mobile app ?
It should look like that -> #define gattdb_ota_control