Errors / JavaScript errors

QuotaExceededError: Failed to execute 'setItem' on 'Storage'

The site tried to save more in the visitor's browser than the browser allows.

Whatever relied on saving (a cart, a preference, a draft) is lost, and the script may stop.

Why it happens

• localStorage is about 5 MB per site, and something keeps adding to it (a cache, a log, a draft) without ever removing.
• Several scripts on the same domain sharing the same space.
• Some private-browsing modes allow little or no storage.

How to fix it

1. Wrap setItem in try/catch: storage is never guaranteed.
2. Store less, expire old entries, or move large data to IndexedDB.
3. To see what fills it, open DevTools' Application panel, then Local Storage for the site: the keys and their sizes are listed, and one growing key is usually the cause. A visitor who hits the limit keeps hitting it on every visit until the data is cleared, so the failure looks permanent to them and random to you.

Whose problem it is

Usually the site's own code or settings.