Let's say something like this is being returned when attempting to use the imcl (Installation Manager command line tool) command line tool.

ERROR: The Installation Manager's registry information is inconsistent with its installation information.
  ERROR: The registry information at "/home/john.doe/etc/.ibm/registry/InstallationManager.dat" indicates that Installation Manager 1.9.2.2 (internal version: 1.9.2002.20220323_1321) is installed at location "/opt/WebSphere/InstallationManager/eclipse" and is using "/home/john.doe/var/ibm/InstallationManager" for its data location. 
  However, the information at the data location indicates that Installation Manager 1.9.1 (internal version: 1.9.1000.20191001_1228) is installed at location "/opt/WebSphere/InstallationManager/eclipse".

Or perhaps this.

ERROR: The Installation Manager's registry information is inconsistent with its installation information.
  ERROR: The registry information at "/home/john.doe/etc/.ibm/registry/InstallationManager.dat" indicates that Installation Manager 1.9.2.2 (internal version: 1.9.2002.20220323_1321) is installed at location "/opt/WebSphere/InstallationManager/eclipse" and is using "/home/john.doe/var/ibm/InstallationManager" for its data location. However, the information at the data location indicates that the Installation Manager is not installed.

Be aware that the last sentence here is relevant.

• However, the information at the data location indicates that Installation Manager 1.9.1 (internal version: 1.9.1000.20191001_1228) is installed at location /opt/WebSphere/InstallationManager/eclipse
• However, the information at the data location indicates that the Installation Manager is not installed

Notice in this example that the error message references /home/john.doe/etc/.ibm/registry/InstallationManager.dat. Ensure this file exists and is owned by the user (john.doe in this example) with -rw-r--r-- permissions (0644).

~]$ ll /home/john.doe/etc/.ibm/registry/
-rw-r--r-- 1 john.doe john.doe 276 Jul 15 03:30 InstallationManager.dat

If InstallationManager.dat does not exist, if you have a similar system, you can try taking a copy of InstallationManager.dat from the similar system and recreating InstallationManager.dat on the system that is missing InstallationManager.dat.

However, the information at the data location indicates that the Installation Manager is not installed

This often suggests that the installed.xsl and installed.xsd and installed.xml files do not exist.

• /home/john.doe/var/ibm/InstallationManager/installed.xsl
• /home/john.doe/var/ibm/InstallationManager/installed.xsd
• /home/john.doe/var/ibm/InstallationManager/installed.xml
• /home/john.doe/var/ibm/InstallationManager/installRegistry.xml

If Installation Manager is the only product being mainted by Installation Manager, then it's probably totally find to just remove the following directories (on a Linux System) and reinstall Installation Manager.

• /home/john.doe/etc
• /home/john.doe/var
• /opt/WebSphere/InstallationManager (or whatever directory Installation Manager is at)

On the other hand, if there are other packages that were installed by Installation Manager, you most definitely should not remove the above directories, as this will make it so much more difficult, if not impossible, to maintain the packages using Installation Manager. When I ran into this issue, fortunately I had sister machines with nearly identical Installation Manager, so what I did was to create a tar archive of the /home/john.doe/var/ibm/InstallationManager on the sister machine.

~]$ cd /home/john.doe/var/ibm
~]$ tar -cpf /tmp/InstallationManager_from_sister_machine.tar InstallationManager/

And to then SCP the tar archive from the sister machine to the machine having the problem with Installation Manager.

scp /tmp/InstallationManager.tar john.doe@server1:/tmp

Then on the machine having the problem with Installation Manager, I renamed the Installation Manager directory.

cd /home/john.doe/var/ibm
mv InstallationManager InstallationManager.backup

And extracted the TAR archive.

tar -xpf /tmp/InstallationManager_from_sister_machine.tar --directory /home/john.doe/var/ibm

And then lo and behold, Installation Manager was working again! Hooray!

~]$ /opt/WebSphere/InstallationManager/eclipse/tools/imcl listInstalledPackages -long
/opt/WebSphere/InstallationManager/eclipse : com.ibm.cic.agent_1.9.2002.20220323_1321 : IBM® Installation Manager : 1.9.2.2
/opt/WebSphere/AppServer : com.ibm.websphere.ND.v85_8.5.5021.20220202_1245 : IBM WebSphere Application Server Network Deployment : 8.5.5.21

However, the information at the data location indicates that Installation Manager is installed at location

If InstallationManager.dat exists, examine the contents of the /home/john.doe/etc/.ibm/registry/InstallationManager.dat file. Notice in this example that version is 1.9.2.2 and internalVersion is 1.9.2002.20220323_1321. However, the error message references version 1.9.1 and internalVersion 1.9.1000.20191001_1228.

~]$ cat /home/john.doe/etc/.ibm/registry/InstallationManager.dat 
#Fri Jul 15 03:30:28 CDT 2022
version=1.9.2.2
location=/opt/WebSphere/InstallationManager
internalVersion=1.9.2002.20220323_1321
registryVersion=1
is64bit=true
appDataLocation=/home/john.doe/var/ibm/InstallationManager
launcher=/opt/WebSphere/InstallationManager/eclipse/IBMIM

In this scenario, you could try to update the InstallationManager.dat file to have version 1.9.1 and internalVersion 1.9.1000.20191001_1228 and then reissue the imcl (Installation Manager command line tool) command line tool to see if this resolves the error.

~]$ cat /home/john.doe/etc/.ibm/registry/InstallationManager.dat 
#Fri Jul 15 03:30:28 CDT 2022
version=1.9.1
location=/opt/WebSphere/InstallationManager
internalVersion=1.9.1000.20191001_1228
registryVersion=1
is64bit=true
appDataLocation=/home/john.doe/var/ibm/InstallationManager
launcher=/opt/WebSphere/InstallationManager/eclipse/IBMIM