title: ASP.NET 4 Membership Machine Key
body: <p>I have had a working asp.net 4 membership wesite for about 5 months and today I changed the regex to loosen the password restrictions. I can still create and access new accounts, but can no longer access any of the previously registered ones.</p>
  
  <p>I have checked the database and confirmed that they are all still there. My initial thought was an incorrect password. I've checked two accounts that I knew the password for and both are inaccessable. I attempted to use the password recovery option, but when I type in the username I'm told that the user does not exist.</p>
  
  <p>When I check the databases and consult both the membership and profile tables, the old and new users, pre and post regex change, are all in the same table. This leads me to my final discovery and the one that I have no experience. Is there a new Machine Key that is creating the new users but cannot decipher the old ones, hence making them unavailable? If so, how can I fix this?</p>