topic Re: Unable to Connect to Analysis Services from Power BI Report Server in Report Server

Unable to Connect to Analysis Services from Power BI Report Server

mariawrightnoor — Thu, 05 Feb 2026 17:45:47 GMT

We are experiencing connectivity issues when rendering Power BI reports on Power BI Report Server.

The error message is:

An unexpected error occurred. Please try again later. We couldn't connect to the Analysis Services server. Make sure you've entered the connection string correctly. Request ID: c78740a0-9cfa-7373-20b3-2fa3ed8f534c Time: Thu Feb 05 2026 09:29:33 GMT-0800 (Pacific Standard Time) Service version: /powerbi/libs

Environment Details:

Power BI Report Server Version: 2026
SQL Server Analysis Services Version: 2021
Authentication Method: [Windows Authentication / Stored Credentials]
Connection String: ep-SQLA01
Report Server Service Account : sa
Data Source Test Connection: Successful
Error occurs when rendering report in Web Portal.

Steps Taken:

Verified connection string.
Tested credentials in Data Source settings (successful).
Restarted Report Server service.
Checked firewall and network connectivity.

Log File Location: C:\Program Files\Microsoft Power BI Report Server\PBIRS\LogFiles

Please advise on resolving SSAS connectivity issues.

Re: Unable to Connect to Analysis Services from Power BI Report Server

v-sgandrathi — Fri, 06 Feb 2026 08:52:00 GMT

Hi mariawrightnoor,

The main reason for this issue is that the Power BI Report Server service account is set as sa, which is a SQL login, not a Windows account. Power BI Report Server needs a Windows (preferably domain) account to securely connect to SQL Server Analysis Services (SSAS). The Test Connection option works because it checks basic connectivity, but the report fails to render in the web portal since SSAS does not support SQL authentication or SQL logins like sa for user impersonation and execution context.

To fix this, update the Power BI Report Server service account to a Windows domain account (e.g., DOMAIN\PBIRS_Service) and restart the service. This allows the report to use a valid Windows security context when connecting to SSAS.

Also, make sure the PBIRS service account has explicit permissions in SSAS. In SQL Server Management Studio, connect to Analysis Services, go to the relevant database, and add the PBIRS service account to an SSAS role with at least Read access. This step is important because SSAS does not grant permissions automatically, even if the connection test passes.

If SSAS is on a different server and Windows Authentication is used, the problem could be due to a Kerberos double-hop limitation. In this case, set up Kerberos delegation with a domain service account or configure the data source to use Stored Credentials (Windows authentication) to avoid impersonation issues.

Check the Power BI Report Server logs at C:\Program Files\Microsoft Power BI Report Server\PBIRS\LogFiles and the SSAS logs for errors like “Login failed,” “NT AUTHORITY\ANONYMOUS LOGON,” or impersonation failures. These errors indicate authentication and service account configuration problems, not network or firewall issues.

In short, switch the sa account to a valid Windows domain service account, grant it access in SSAS, and restart both services to resolve the SSAS connectivity error when rendering reports in the Power BI Report Server web portal.

Thankyou.

Re: Unable to Connect to Analysis Services from Power BI Report Server

v-sgandrathi — Mon, 09 Feb 2026 05:04:36 GMT

Hi mariawrightnoor,

we haven't heard back from you regarding our last response and wanted to check if your issue has been resolved.

Should you have any further questions, feel free to reach out.
Thank you for being a part of the Microsoft Fabric Community Forum!

Re: Unable to Connect to Analysis Services from Power BI Report Server

v-sgandrathi — Thu, 12 Feb 2026 05:59:14 GMT

Hi mariawrightnoor,

I wanted to follow up on our previous suggestions regarding the issue. We would love to hear back from you to ensure we can assist you further.

Thank you.

Re: Unable to Connect to Analysis Services from Power BI Report Server

mrusu — Thu, 12 Feb 2026 20:17:15 GMT

Experiencing exactly the same issue, it never happened with previous RS versions. Power BI Report Server service account is set as a Windows domain account.

Re: Unable to Connect to Analysis Services from Power BI Report Server

v-sgandrathi — Mon, 16 Feb 2026 11:26:13 GMT

Hi mrusu,

Since you’re already using a Windows domain account for the Power BI Report Server service, this likely isn’t related to the earlier SQL login issue. Because the issue started after upgrading to Power BI Report Server 2026 and didn’t happen with previous versions, it’s probably due to changes in authentication flow, Kerberos delegation, or stricter security. Even if the test connection to the data source works, reports use the PBIRS service account’s context, so make sure this account has explicit permissions in SQL Server Analysis Services (SSAS). In SQL Server Management Studio, connect to SSAS, check the relevant database, and confirm the PBIRS service account is added to a role with at least Read access, and check server-level permissions if needed.

If SSAS is on another server, this might be a Kerberos double-hop issue, which recent PBIRS versions may enforce more strictly. Review the PBIRS and SSAS logs for errors like “NT AUTHORITY\ANONYMOUS LOGON” or login failures, which indicate delegation problems. If so, check that SPNs are registered and constrained delegation is set up correctly. You can also try switching the data source to use Stored Credentials (Windows authentication) temporarily; if the report works, it points to an impersonation or delegation issue. Finally, ensure you’re using the fully qualified domain name in the SSAS connection string and check for any new TLS or encryption restrictions after the upgrade.

Thank you
Community Member.

Re: Unable to Connect to Analysis Services from Power BI Report Server

Andrikano — Tue, 17 Feb 2026 13:29:00 GMT

Check this for January 2026 version. If you look at the contents of the "C:\Program Files\Microsoft Power BI Report Server\PBIRS\LogFiles\" directory, it's overflowing with large files "Msmdsrv.SQLDmpr.*.log", "Msmdsrv.SQLDmpr.*.mdmp" and "SQLDUMPER_ERRORLOG.log". After a while, the disk space may run out. If your disk space run out then AS Engine will be unable to get resources to load models. If you have this situation then clean LogFiles folder from Dmpr files and AS Engine will be working again.

Re: Unable to Connect to Analysis Services from Power BI Report Server

mrusu — Tue, 17 Feb 2026 15:05:05 GMT

Thank you Andrikano, just noticed space on disk became very low, indeed !

Is it safe just to delete everything in "C:\Program Files\Microsoft Power BI Report Server\PBIRS\LogFiles\" ?

Re: Unable to Connect to Analysis Services from Power BI Report Server

Andrikano — Tue, 17 Feb 2026 15:20:57 GMT

Yes, it's absolutely safe. You can't delete files in use, about other files you should decide by yourself if you want to store them. In my opinion you should delete all files: "Msmdsrv.SQLDmpr.*.log", "Msmdsrv.SQLDmpr.*.mdmp" and "SQLDUMPER_ERRORLOG.log" - it can be automated using script to prevent overflow in the future (until this bug will be resolved in update).

Re: Unable to Connect to Analysis Services from Power BI Report Server

mrusu — Tue, 17 Feb 2026 16:22:39 GMT

Thank you Andrikano, for your help, how can I mark this as 'solution'?