How to work around error from opatch "LsInventorySession failed: OracleHomeInventory gets null oracleHomeInfo"

I recently had to investigate the patch level for an Oracle 10g database prior to an upgrade of an OAS application database.

This is the error I ran into:

myserver:asdb:ora10g>opatch lsinventory
Invoking OPatch 10.2.0.4.3

 
Inventory load failed... OPatch cannot load inventory for the given Oracle Home.
Possible causes are:
   Oracle Home dir. path does not exist in Central Inventory
   Oracle Home is a symbolic link
   Oracle Home inventory is corrupted
LsInventorySession failed: OracleHomeInventory gets null oracleHomeInfo

OPatch failed with error code 73

Fix this by running the attachHome.sh script in $ORACLE_HOME/oui/bin.
The Oracle Universal Installer allows you to set up an Inventory from scratch, or to register an existing ORACLE_HOME in an already existing Inventory.

myserver:asdb:ora10g>cd $ORACLE_HOME/oui/bin
/u01/oracle/product/ora10g/oui/bin
myserver:asdb:ora10g>./attachHome.sh
Starting Oracle Universal Installer...

No pre-requisite checks found in oraparam.ini, no system pre-requisite checks will be executed.
The inventory pointer is located at /etc/oraInst.loc
The inventory is located at /u01/oracle/oraInventory11g
'AttachHome' was successful.

Result:

myserver:asdb:ora10g>opatch lsinventory
Invoking OPatch 10.2.0.4.3

Oracle Interim Patch Installer version 10.2.0.4.3
Copyright (c) 2007, Oracle Corporation.  All rights reserved.


Oracle Home       : /u01/oracle/product/ora10g
Central Inventory : /u01/oracle/oraInventory11g
   from           : /etc/oraInst.loc
OPatch version    : 10.2.0.4.3
OUI version       : 10.2.0.4.0
OUI location      : /u01/oracle/product/ora10g/oui
Log file location : /u01/oracle/product/ora10g/cfgtoollogs/opatch/opatch2016-01-18_16-01-17PM.log

Lsinventory Output file location : /u01/oracle/product/ora10g/cfgtoollogs/opatch/lsinv/lsinventory2016-01-18_16-01-17PM.txt

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Installed Top-level Products (4):

Oracle Database 10g                                                  10.2.0.1.0
Oracle Database 10g Products                                         10.2.0.1.0
Oracle Database 10g Release 2 Patch Set 2                            10.2.0.3.0
Oracle Database 10g Release 2 Patch Set 3                            10.2.0.4.0
There are 4 products installed in this Oracle Home.


Interim patches (3) :

Patch  6979801      : applied on Fri Mar 06 10:47:02 CET 2009
   Created on 5 Feb 2009, 15:35:25 hrs PST8PDT
   Bugs fixed:
     6979801

Patch  6972843      : applied on Tue Oct 14 17:35:12 CEST 2008
   Created on 25 Jun 2008, 08:31:04 hrs UTC
   Bugs fixed:
     6972843

Patch  6823287      : applied on Tue Oct 14 17:26:32 CEST 2008
   Created on 30 Jun 2008, 10:27:42 hrs UTC
   Bugs fixed:
     6823287



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OPatch succeeded.