Developer Documents Key MV3 Chrome Extension Pitfalls and Their Fixes

A developer building the TokenPulse Chrome extension under Manifest V3 encountered multiple silent failures and cryptic errors that only surfaced in production. MV3 enforces strict Content Security Policies, requiring all inline JavaScript to be moved into external files, a change that affected 23 event handlers across the project. Service workers in MV3 are non-persistent and can be killed by Chrome after roughly 30 seconds, meaning in-memory state and async message listeners must be restructured to use chrome.storage and synchronous returns. Scripts injected by content scripts must be explicitly declared in the manifest's web_accessible_resources field, and Chrome APIs such as alarms and notifications fail silently when their required permissions are missing from the manifest. The developer shared each problem and its corresponding fix as a practical reference for others migrating extensions from MV2 to MV3.