JSONSerialization Invalid JSON

iOS

TL;DR

JSONSerialization Invalid JSON indicates a parsing failure on iOS that interrupts the current user flow.

Symptoms

JSONSerialization Invalid JSON appears in crash logs
The app exits or the UI flow stops

Common Causes

Payload shape differs from expected schema
Decoder assumptions are not validated

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

JSONSerialization Invalid JSON in ProfileViewController.swift:42

Related Errors

IllegalStateException Unhandled Promise Rejection Hydration Failed