Oracle Database 19.31 Patch Hold: What DBAs on Exadata 25.2 Need to Know

If you’ve been trying to download the latest Oracle Database 19.31 Release Update (RU) lately and found the download pages curiously empty, you aren't alone. Oracle has officially placed a temporary hold on this specific RU for Exadata environments.

The move comes after several customers reported intermittent internal errors specifically when running 19.31 on Exadata System Software 25.2. Here is a breakdown of what happened, why it matters, and how to keep your systems stable.

What’s the Problem?
Oracle recently published a My Oracle Support (MOS) advisory regarding a conflict between the 19.31 DBRU and the newer Exadata 25.2 software stack. It appears that a specific optimization path related to temporary tablespace processing is triggering internal failures during SQL execution.

Because the issue is severe enough to cause application instability, Oracle took the proactive step of removing the 19.31 patch binaries while they work on a corrected revision.
Key Symptoms to Watch For:
If you are already on this combination, you might see a spike in:

• ORA-00600 internal errors (specifically signatures like QERHNITERATEOVERBUFFERS.1 or kcblsltio_1)
• Unexpected SQL statement failures and session terminations
• Background process crashes that disrupt application uptime

Issues specifically during heavy ETL, analytics, or workloads that lean hard on temporary segments.

Workaround: Disabling the Optimization
If you have already deployed 19.31 to your Exadata 25.2 environment, you don't necessarily need to roll back immediately. Oracle has provided a "hidden parameter" workaround that disables the problematic optimization path.

To mitigate the risk immediately, run the following:
-- For the current instance
alter system set "_kcfis_fctempopt_mode" = 0;

-- For RAC environments (persistent across nodes)
alter system set "_kcfis_fctempopt_mode" = 0 scope=both sid='*';

Note: As with any hidden parameter, make sure to document this in your operational runbook and monitor performance. Once Oracle releases the corrected RU, you will likely need to unset this parameter.

Who is Affected?
The good news is that this is a relatively narrow issue. It currently only impacts:
Database Version: 19.31
Infrastructure: Exadata System Software 25.2.*
If you are running 19.31 on standard Linux/Unix servers, or if your Exadata units are on older software versions, you are likely in the clear.

reference: We released a MOS Note with detailed information: (KB888427) Oracle Database 19.31 Patch Hold Due to ORA-00600 Errors on Exadata 25.2: