NetworkOnMainThreadException

Android

TL;DR

NetworkOnMainThreadException indicates a network failure on Android that interrupts the current user flow.

Symptoms

NetworkOnMainThreadException appears in logcat
The app crashes or the action fails

Common Causes

Endpoint or DNS is unreachable
TLS, transport, or request policy rejects the call

How to Verify

Reproduce with deterministic input and capture full logsInspect the first throw site and recent changes around it

Quick Fixes

Add guard checks and a safe fallback path
Disable or rollback the risky code path behind a flag

Proper Fixes

Enforce contracts with types, runtime checks, and tests
Refactor ownership and lifecycle boundaries to remove the failure mode

Example Stack Trace

NetworkOnMainThreadException at com.example.app.MainActivity.onCreate(MainActivity.kt:42)

Related Errors

NSInvalidArgumentException TypeError Cannot Read Properties Of Undefined NetworkError Failed To Fetch