SOLVED: Power BI to Oracle Refresh Fails with ORA-03113: end-of-file on communication channel

Body of your Stack Overflow answer:

I'm posting this detailed answer because my team and I finally solved this exact issue. The solution was not in Power BI or a database permission, but a specific conflict between our Oracle Client's protocol and our corporate firewall.

This was the final step after a long troubleshooting process, and hopefully, it can help someone else.

The Symptoms

• We were connecting Power BI Desktop to an Oracle database.

• The initial connection and small data previews in the Power Query Editor worked fine.

• The ORA-03113: end-of-file on communication channel error appeared only when performing a full data refresh on large tables.

The Diagnosis: Firewall vs. Oracle Protocol

After working with our IT department, we found the root cause in our Check Point firewall logs. The firewall was dropping packets with the following message:

"TCP segment with urgent pointer. Urgent data indication was stripped."

The problem was a conflict:

1. Oracle's Protocol (SQL*Net): Uses TCP packets with the URG flag for its "Out-of-Band Break" mechanism, which can be used to cancel long-running queries.

2. Our Firewall's Policy: By default, our Check Point firewall considered packets with the URG flag a security risk and was terminating the connection whenever it detected them during the large data transfer.

Our Solution: Modifying the Oracle Client Configuration

Instead of changing the corporate firewall policy, we chose to fix this on the client side, as it was faster for us to implement. We instructed our Oracle client to simply not use this "out-of-band" mechanism.

Here are the exact steps that worked for us:

1. Identify the Correct Client Software: The machine running Power BI Desktop was using the Oracle Client for Microsoft Tools (OCMT).

2. Locate the sqlnet.ora File: We needed to edit the sqlnet.ora configuration file. We found it inside the OCMT installation directory. The path was: [ORACLE_CLIENT_INSTALL_DIRECTORY]\network\admin (For example: C:\oracle\product\19.0.0\client_1\network\admin)

   Note: If the sqlnet.ora file does not exist in this folder, you can simply create it as a new, empty text file.

3. Add the Configuration Parameter: We opened the sqlnet.ora file with a text editor and added the following line:

   DISABLE_OOB=ON
   
   

4. Apply Changes: We saved the sqlnet.ora file and then restarted Power BI Desktop.

After this change, the full data refresh worked perfectly without any ORA-03113 errors.

Alternative Solution (Firewall-Side)

For completeness, the other possible solution is to have the network security team create an exception in the firewall. This would involve modifying the security policy (in our case, for Check Point) to allow TCP packets with the URG flag, but only for the specific traffic between the Power BI client/gateway and the Oracle database server.

I hope our experience helps other users facing this frustrating issue