Here I am with another problem and the possible solution to it. I am saying “possible” solution cause I believe that solution might be case dependent.
Let's talk about my case. When I encountered this error message I was trying to install nopCommerce using Web PI. Web PI completed all the downloading and at some point during the installation it prompted for database credentials. I entered the password for the “sa” user for my “.SQLEXPRESS” database and bam! I got the error message below.
Then I opened up the Sql Server Management Studio and tried to connect to “.SQLEXPRESS” database using “SQL Server Authentication” with “sa” account.
That is where I saw the second error message which would lead me to the solution. Error message was saying “Login failed for user 'sa'. Reason: The account is disabled.”
Here are the steps to re-enable the sa account:
1- Change the “Authentication” type to “Windows Authentication” and connected to the database
2- Browse to Security->Logins->sa
3- Right-click sa and click properties
4- Click “Status”
5- Change “Login” to “Enabled”
6- Click “OK”
Now that the sa account was re-enabled, I would retry the installation and voila! The problem was solved, installation completed!
Hope this helps someone.