Which application to put the blame on?

Ever experiences a failed installation? I have… many times.
Ever experienced that an installation f*ck*d up a driver? I have…many times.
Ever experienced a sad feeling because you couldn’t find out which application did it? I have… many times.

Finaly, now that is over. Alright, you will still have the problem, but now you can deduce which application did it.

For this example I have used the Citrix Online Plug-in:

I have installed it some time ago and now it stopped working, just like that.
Of course I am playing the typical user and “no, nothing has changed in my environment”…

Lets just take for granted here that the user (like…me?) has had a failed installation of an application. Normally an application will roll back it’s action, but again let’s take for granted here that it’s not done properly.
In those cases I get scared…
But now… my Citrix Online Plug-in is not working and (as a user) I have got no clue why…
First of all, does a re-installation of the product do the trick? No?
Then let’s start troubleshooting…

In these cases I always suspect that an application has re-registered a dll-file, a file has been overwritten or a registry key has been changed.
Those first two options are just about always covered when you re-install an application.
So if that is not working, then my guess will be that a registry key has a changed. Many installations look at the registry, see that the key is present and only check if they are there but don’t check the values…

Let’s take such a key:
Now the only thing I really miss in Windows Registry Editor is a to see a timestamp… when was the last time a key has been changed?

A few years back I stumbled upon this tool, the Registry Commander:

Now as you can see it does provide a timestamp!

The mechanism of timestamps in the registry is very simple… if they key or anything underneath it is changed, the timestamp is changed.
So in this case you can simply follow the tree and deduce which key has been changed…and when!

How is that information useful?
Just go to your “Control Panel –> Add and remove programs”  There you can look for an application that has been installed on that specific date.
In my case, the Citrix Online Plugin has been installed on:

And the only application that has been installed at the time my registry key has been changed:

Logic dictates is likely that the application which has been installed on the same date that the registry key has been changed is the cause.

And yes, I’ve made the installation of the application fail… therefore I was able to reproduce this issue just for this blog post.
Note that I’ve just taken these applications as an example… the issue can occur with any set of applications.

Happy hunting!

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