ASP.NET membership provider ValidateUser() returns false intermittently

Question

We have a strange production issue with the ASP.NET Membership Provider that we have been unable to resolve. When the issue occurs, ValidateUser() returns false even when valid credentials are entered, the user is approved, and the user is not locked out. The problem occurs randomly about once or twice a week, and it requires an app pool recycle to resolve. After the recycle, users are able to log in without issue. Also, multiple login attempts during this time window do not cause users to become locked out.

Any idea why this might happen or how we can troubleshoot the issue when it occurs? ValidateUser only returns a bool, so I don't have much to go on.

Answer 1

It could be a lot of things. However, the symptoms point to two or three likely scenarios.

1. Your membership provider instance has been replaced with a different provider somehow (rogue code? an = when you meant an ==?, who knows?)
2. Your database connection pool has become corrupt, fragmented, or confused.
3. Your database configuration has somehow become corrupted

All three would get fixed with an app pool recycle. Finding the cause could be tough.