A number of bugs have been filed since Firefox 70 release that report site breakage that's consistent with LocalStorage throwing errors. The plan is to turn off LocalStorage on release in the first available dot release.
We currently believe what we're seeing to be a mixture of 2 things:
- Most Common: QuotaManager storage initialization failures cascading into LocalStorage breakage.
- Least Common: Edge cases related to unexpected LSNG corruption that are not properly recovered from. We have at least one report where it seems that the database has 2 zeroed pages that results in a corruption error at query time but not at database open time.
- The corruption superficially looks hardware-related, but we have not yet ruled out the possibility of improvements in browser shutdown leaving a database in an inconsistent state.
Next steps will be to add improved telemetry that can characterize the health of the LocalStorage API and what failures are happening.
I'm currently marking known manifestations of the problem as blocked by this bug.