FIX : The password supplied with the username Domain\Username was not correct. Verify that it was entered correctly and try again.

This will happen often while trying to create a new web application in SharePoint 2013 central administration site.
It gives the following error

This usually occur when farm account password is expire and it's password is changed or simply farm account password is changed. In that case, sometimes password stored in SharePoint database is different in Active Directory, so unable to create web application from central admin.

 In order to resolve this problem you need to update SharePoint 2013 farm credentials using "STSADM" tool.

For that Open PowerShell in administration mode

then write the following code

stsadm -o updatefarmcredentials -userlogin <UserAccount> -password <New-password>

Example:

Once you receive operation completed successfully message do a IIS reset !!

FYI : In case if you getting an error message "stsadm not recognized as an internal command"

Follow these instructions..

Happy Coding !!