What causing this “Invalid length for a Base-64 char array”

Question

I have very little to go on here. I can\'t reproduce this locally, but when users get the error I get an automatic email exception notification:

Answer 1

During initial testing for Membership.ValidateUser with a SqlMembershipProvider, I use a hash (SHA1) algorithm combined with a salt, and, if I changed the salt length to a length not divisible by four, I received this error.

I have not tried any of the fixes above, but if the salt is being altered, this may help someone pinpoint that as the source of this particular error.