We’re experiencing persistent credential failures when refreshing datasets that use shared data sources in SSRS 2014. The error appears immediately after the dataset refresh is triggered: ‘Cannot connect to data source - authentication failed’. Our shared data source is configured to use stored credentials with a service account that has verified database permissions. The credential storage and encryption seem intact as other reports using the same shared data source work fine. However, when we attempt to refresh specific datasets in Report Manager, the authentication consistently fails. We’ve checked the service account permissions at both the SQL Server and SSRS levels, and they appear correct. The connection string in the shared data source configuration looks properly formatted. Has anyone encountered similar issues with credential handling during dataset refresh operations?
We’re using SQL Authentication with stored credentials. The service account definitely has database access - I can connect manually using the same credentials through SSMS. The RSReportServer.config hasn’t been modified recently. What’s puzzling is that some datasets refresh successfully while others fail, all using the identical shared data source.
Your parameter observation is the key here. This is a known issue in SSRS 2014 where parameterized dataset queries can fail credential validation during refresh if the parameters aren’t properly initialized. Here’s the complete solution:
Shared Data Source Configuration: First, verify your shared data source credential storage is correct. In Report Manager, edit the shared data source and ensure ‘Credentials stored securely in the report server’ is selected with ‘Use as Windows credentials when connecting to the data source’ UNCHECKED for SQL Authentication.
Dataset Parameter Initialization: The core issue is that SSRS 2014 requires default values for ALL dataset parameters during refresh operations. Edit each failing dataset and ensure every parameter has a valid default value defined. Even if the parameter is normally supplied at runtime, it needs a default for refresh scenarios.
-- In your dataset query, use ISNULL for parameter safety:
SELECT * FROM Sales
WHERE RegionID = ISNULL(@RegionParam, 1)
Service Account Permissions: Verify the SSRS service account has these specific permissions:
- SQL Server: db_datareader on target databases
- ReportServer database: RSExecRole membership
- Windows: ‘Log on as a service’ and ‘Log on as a batch job’ rights
Credential Encryption Validation: Run this query against ReportServer database to check credential integrity:
SELECT Name, Type, CredentialRetrieval
FROM Catalog
WHERE Type = 5 -- Data Sources
If CredentialRetrieval = 2, credentials are stored. If you see any NULL values, the encryption is corrupted and you’ll need to re-enter credentials.
Connection String Configuration: Ensure your connection string doesn’t include credentials (they should be in the separate credential section):
Data Source=SQLServer01;Initial Catalog=SalesDB
Testing Process:
- Create a test dataset with no parameters using the same shared data source
- If it refreshes successfully, the issue is parameter-related
- Add default values to all parameters in failing datasets
- Clear the report server cache: delete contents of ReportServer TempDB
- Test refresh again
This approach has resolved similar issues in multiple SSRS 2014 environments. The parameter initialization requirement is particularly important for scheduled refresh operations where no user context exists to provide parameter values.
Check the dataset query timeout settings. If your refresh queries are complex or hitting large tables, they might be timing out before credential validation completes. Also, look at the ReportServer database logs - there should be more detailed error information in the ExecutionLog table that might reveal if it’s actually a timeout being misreported as an authentication error.