I'm receiving the following error when trying to do a PDO OCI SQL query on one of my web servers:

```
SQLSTATE[HY000]: OCISessionBegin: ORA-21561: OID generation failed

```

I've confirmed that the Oracle server is accessible from the machine and network configuration looks fine. Google returns very few, and not very helpful results.

Has anyone else run into this, or have any suggestions on how to resolve?