Last year, Chrome introduced manifest V2 to Apps and Extension developers, which brings a variety of security and API improvements such as a default Content Security Policy. As of Chrome 18, manifest V1 was officially deprecated. At the time, we published our manifest version support schedule to give developers transparency and insight into our plans for migrating to the new version.
Today, we’re announcing a slight update to that schedule, to let developers know that they have until Monday, March 4, 2013 to make updates to their existing manifest V1-based items. After that date, the Chrome Web Store will block all updates to products based on manifest V1 unless the update includes switching it to manifest V2.
Developers are strongly encouraged to migrate their items to manifest V2 now. Follow the migration tutorial, and you can always contact us on the chromium-apps forum and our G+ page with any questions you may have.