'java.lang.String com.activeandroid.TableInfo.getTableName()' on a null object reference

[runat3]

With this code, the problem persists.

<meta-data
    android:name="AA_MODELS"
    android:value="com.myapp.model.Item, com.myapp.model.Category" />

Then I found that by removing the space, it worked
like this

<meta-data
    android:name="AA_MODELS"
    android:value="com.myapp.model.Item,[No space here]com.myapp.model.Category" />

[ImangazalievM]

Hello. ActiveAndroid no longer be maintained. You can use ReActiveAndroid, it's based on ActiveAndroid.

Full Documentation.

[WahidNasri]

try to disable instant run

[deepankar-np]

try to disable instant run

Yes, It is working after disabling instant run. I also invalidated and restarted the android studio.
However, after reinstalling the APKit was again throwing the same error. Hence, I cleared the app data and after that, the app again started working.

[ReejeshPK]

try to disable instant run

That really helped. Thanks!