I want to bring to your focus a very minor detail which could eat-up your time when it happens.
This is the case when your SSRS report is deployed on ReportServer and you are accessing thru any application or interface e.g. SharePoint. Your SSRS report is using Integrated Security and hence no need to provide Username and Password if you have access to the Report. And everything works fine up to this point.
After some days, if you notice that your SSRS Report is not working as expected and it has started asking for Username and Password while executing it. What could be the reason?
Well, there are many reasons, but one of the reasons could be “Your windows password has expired which you use for accessing SSRS Report“.
Note: This could happen if your login has password expiration policy in place. And your credentials are used in Data Source of SSRS Report for configuration.
That’s why it’s always safe to use kind of Service Account which is common for accessing Reports and probably with no password expiration policy.
I think you got my point.