If you have the error “Could not save password reset key to database.”, more than likely you have one of the following issues:
- Database server is full (the values cannot be saved to the database due to the file system being 100% full)
- Database server is read-only (If you use a service such as Amazon Web Service’s RDS your website may be connecting to the read replica instead of the write server)
- Database cannot make changes to database tables (check the database files can be written to by the user the database service is running as)
- Temporary folder on your server is not writable (this is the least likely scenario)
I found this problem is not documented well so I blogged my research. Hopefully this helps others searching for a solution.