ADB server version (40) doesn't match this client (41) {Not using Genymotion}
Since this adb server version (XX) doesn't match this client (YY); killing... seems to be a very prominent question, let me present the quite straight forward solution - I actually wonder why it wasn't answered anywhere else or at least, I couldn't find it. To find the version of ADB you are using, type adb version to get something like:
Android Debug Bridge version 1.0.41
Version 30.0.5-6877874
Installed as D:\Setups\XXXXX\Lineage FP3\platform-tools_30.0.5(ADB_1.0.41)\adb.exe

The Android version simply doesn't match the adb version. Android 11 for example uses the API 30 and ADB 41. Android 10 (API 29) and that phone needs ADB 40. You can check your Android version to find the corresponding ADB version to get or easily read the error message above to find XX (in this case 40).
I was able to find ADB version 1.0.40 from here and it works like a charm:
D:\Setups\XXXXX\Lineage FP3\platform-tools_28.0.1(ADB_1.0.40)&gt;adb devices
List of devices attached
A2XXXXXXXXX1    unauthorized