This article explains why a User may have to reset their password on every login.
A User tries logging into Salesforce with their current username and password, but receives the following error:
"You have attempted to access a page that requires a salesforce.com login. If you are already a user of the system please login below."
The user resets the password and is able to log in, however when they log out and try to log back in, they are unable to use the same password. The login attempt may even show as "successful" in the login history for the user.
This issue is resolved with some basic browser modifications, including clearing cache and adding Trusted Sites. Review the steps for the web browsers below:
If you're using a custom bookmarked URL to log in (that is, a URL that contains the username and password in it), please be aware that this is not supported or recommended. If you want to have a bookmark to the native Salesforce login page, it should point to https://login.salesforce.com/ for production and https://test.salesforce.com/ for sandboxes.
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