[reporting-services] Cannot create a connection to data source Error (rsErrorOpeningConnection) in SSRS

I'm working on integrating a report into a browser, and I get this error:

An error has occurred during report processing. (rsProcessingAborted)
Cannot create a connection to data source 'dsFederatedSample_SurveyLevel_STG'. (rsErrorOpeningConnection)
For more information about this error navigate to the report server on the local server machine, or enable remote errors

Does this have to do with SQL vs Windows authentication?

The issue is because your data source is not setup properly, to do that please verify your data source connection, in order to do that first navigate to Report Service Configuration Manager through

clicking on the start -> Start All -> Microsoft SQL Server ->Configuration Tool -> “Report Service Configuration Manager”

The open Report Manager URL and then navigate to the Data Source folder, see in the picture below

Then Create a Data Source or configure the one that is already there by right click on your database source and select "Manage" as is shown below

Now on the properties tab, on your left menu, fill out the data source with your connection string and username and password, after that click on test connection, and if the connection was successful, then click "Apply"

Navigate to the folder that contains your report in this case "SurveyLevelReport"

And Finally set your Report to the Data Source that you set up previously, and click Apply

if you use null values in your stored procedure, you will need to set the parameters to accept null values. That worked for me.

I had a similar problem, and being the newbie that I am it took me a while to figure out but I learned the user must have a login in SSMS. I created the logins with the following parameters:

• Under Server Roles - check sysadmin
• Under User Mapping - I selected the database and the report server. For each I checked datareader and datawriter
• Under Securables - I checked anything that would allow the user to connect to the database and view anything
• I also found that one of the existing logins had denydatareader and denydatawriter checked. Once I removed these it worked.

I'm not saying this is the best way to do it, just what worked for me. Hope this helps

More information will be useful.

When I was faced with the same error message all I had to do was to correctly configure the credentials page of the DataSource(I am using Report Builder 3). if you chose the default, the report would work fine in Report Builder but would fail on the Report Server.

You may review more details of this fix here: https://hodentekmsss.blogspot.com/2017/05/fix-for-rserroropeningconnection-in.html

In my case I had in one report many different datasets to DB and Analysis Services Cube. Looks like that datasets blocked each other and generated such error. For me helped option "Use single transaction when processing the queries" in the CUBE datasource properties

I had the same issue "Cannot create a connection to data source...Login failed for user.." on Windows 8.1, SQL Server 2014 Developer Edition and Visual Studio 2013 Pro. All solutions offered above by other Stackoverflow Community members did not work for me.

So, I did the next steps (running all Windows applications as Administrator):

1. VS2013 SSRS: I converted my Data Source to Shared Data Source (.rds) with Windows Authentication (Integrated Security) on the Right Pane "Solution Explorer".

2. Original (non-shared) Data Source (on the Left Pane "Report Data") got "Don't Use Credentials".

3. On the Project Properties, I set for "Deployment" "Overwrite DataSources" to "True" and redeployed the Project.

After that, I could run my report without further requirements to enter Credentials. All Shared DataSources were deployed in a separate Directory "DataSources".

I had the exact same issue. The cause could be different but in my case, after trying several different things like changing the connection string on the Data Source setup, I found that this was the infamous 'double hop' issue (more info here).

To solve the problem, the following two options are available (as per one of the responses from the hyperlink):

1.   Change the Report Server service to run under a domain user account, and register a SPN for the account.
   

2.   Map Built-in accounts HTTP SPN to a Host SPN.
   

Using option 1, you need to select 'Windows' credentials instead of database credentials to overcome the double hop that happens while authentication.

In my case, this was due to using Integrated Windows Authentication in my data sources while developing reports locally, however once they made it to the report manager, the authentication was broke because the site wasn't properly passing along my credentials.

• The simple fix is to hardcode a username/password into your datasource.
• The harder fix is to properly impersonate/delegate your windows credentials through the report manager, to the underlying datasource.

In SQL Server 2008 in addition to the above two options you have a third option to make this setting through SQL Server Management Studio.

1.Start Management Studio and connect to Report Server Instance (make sure you select 'Reporting Services' server type).

2.Right click on the ReportServer and Select Properties

3.Click Advanced

4.In EnableRemoteErrors, select True.

5.Click OK.