How to fix “mutation operation” errors in Firefox
“A mutation operation was attempted on a database that did not allow mutations”
The solution is to make sure dom.indexedDB.enabled is set to true in about:config
One example of a website with this problem is weather.com which will not display anything on the page unless this setting is enabled. Developers should wrap such function calls in try/catch or other error handling so your entire website doesn’t fail. Browser sniffing is not adequate.