Re: Recurrent problem ORA -12560

On Jun 3, 5:30 pm, benn..._at_poczta.fm wrote:
> Hi,
> I know that this topic has been under discussion several times,however
> I couldn't find proper solution.
> I've installed Oracle XE 10g on my PC and when trying to connect from
> Pl-SQL an error occurs.
> Ora-12560 Tns: protocol adapter error.
> Can somebody explain it to me step by step, what I should do in order
> to connect to the database.
> I would be very grateful if somebody could help me.

There are several possible reasons. Most common reason for this, in my experience, is that the database and listener were installed on a machine that uses DHCP to get it's IP address AND has an automatically assigned host name.

On install, the LISTENER.ORA file gets filled with the host name at the time of install.

Some time, and a few reboots, later the listener is told to start up. It reads the LISTENER.ORA file and attempts to start up and listen on behalf of the host listed in the file. But that host name is either no longer valid (or worse - in use by another computer) because of the DHCP reassignment. The result is the TCP/IP protocol adapter can not function correctly - a Protocol Adapter Error (aka ORA-12560).

Since this is a common occurance on Windows-based XE installs, and since you don't mention the OS (something else very common by anyone using Windows), I assume you are using Microsoft Windows XP ...

This is perhaps the best reason for making sure that you install the Microsoft's loopback adapter (search the MS Knowledge base) _before_ installing XE.

Quick but temporary fix - if this is indeed the problem - is to update the LISTENER.ORA (and TNSNAMES.ORA) file with the 'current' host name.

--
Hans Forbrich   (mailto: Fuzzy.GreyBeard_at_gmail.com)
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