Already Installed Error Message not showing - dialog

Question

I am building an MSI with custom dialogs, but I am not customizing the Welcome Dialog. I have a valid Product ID and Upgrade ID and AllowSameVersionUpgrades is also not there. The following is the UI code, which is being referenced in my Product.wxs.
<?xml version="1.0" encoding="UTF-8"?>
<Wix xmlns="http://schemas.microsoft.com/wix/2006/wi">
<Fragment>
<WixVariable Id="WixUIBannerBmp" Value="Images\Banner.bmp" />
<WixVariable Id="WixUIDialogBmp" Value="Images\dialog.bmp" />
<UI Id="CustomUI">
<TextStyle Id="WixUI_Font_Normal" FaceName="Tahoma" Size="8" />
<TextStyle Id="WixUI_Font_Bigger" FaceName="Tahoma" Size="12" />
<TextStyle Id="WixUI_Font_Title" FaceName="Tahoma" Size="9" Bold="yes" />
<Property Id="DefaultUIFont" Value="WixUI_Font_Normal" />
<!--Standard Dialog References needed to compile-Starts-->
<DialogRef Id="WelcomeDlg" />
<DialogRef Id="DiskCostDlg" />
<DialogRef Id="ErrorDlg" />
<DialogRef Id="FatalError" />
<DialogRef Id="FilesInUse" />
<DialogRef Id="UserExit" />
<!--Standard Dialog References needed to compile-Ends-->
<DialogRef Id="CustLicenseAgmtDlg"/>
<DialogRef Id="InstallDlg"/>
<Publish Dialog="ExitDialog" Control="Finish" Event="EndDialog" Value="Return" Order="999">1</Publish>
<Publish Dialog="WelcomeDlg" Control="Next" Event="NewDialog" Value="CustLicenseAgmtDlg">NOT Installed AND NOT PATCH</Publish>
<Publish Dialog="CustLicenseAgmtDlg" Control="Back" Event="NewDialog" Value="WelcomeDlg">1</Publish>
<Publish Dialog="CustLicenseAgmtDlg" Control="Next" Event="NewDialog" Value="BrowsePathDlg">1</Publish>
<Publish Dialog="BrowsePathDlg" Control="Back" Event="NewDialog" Value="CustLicenseAgmtDlg">1</Publish>
<Publish Dialog="BrowsePathDlg" Control="Next" Event="NewDialog" Value="InstallDlg">1</Publish>
<Publish Dialog="InstallDlg" Control="Back" Event="NewDialog" Value="BrowsePathDlg">1</Publish>
</UI>
<InstallUISequence>
<Show Dialog="WelcomeDlg" Before="ProgressDlg">NOT Installed OR PATCH</Show>
</InstallUISequence>
<UIRef Id="WixUI_Common" />
<UIRef Id="WixUI_ErrorProgressText" />
</Fragment>
</Wix>
First time, the installer runs fine and installs the files. But from the next time, it is not showing the error that, it is already installed. Rather it jumps from the first to the last screen in a flash. But if I rebuild this MSI project in VS and run the new installer, it shows the error. I am not sure what am I doing wrong. Can anyone please help?

Answer 1

You are confusing what 'being installed' means.
You explicitly have a condition on showing your WelcomeDlg of NOT Installed OR PATCH this means you'll never show your WelcomeDlg when your product is already installed. "Installed" in this case is the special property that is set when this product is already installed.
The confusion is probably around "this product". What this means is that the installer with the same product GUID is already present on the system.
I'm guessing you have <Product Id="*"> in your installer. When you rebuild you get another Product GUID so when you run that new installer you built, even though it has everything else exactly the same as your old installer, the Product GUID is different. In Windows' eyes, this is a completely separate product so it will not set the "Installed" property and you'll show your welcome dialog. Since you, I assume, have some property that is set when your product is installed, it will show your "Already installed" error.
If you set your display condition to just 1 I think you'll get the behaviour you are expecting.
<InstallUISequence>
<Show Dialog="WelcomeDlg" Before="ProgressDlg">1 AND NOT REMOVE~="ALL"</Show>
</InstallUISequence>
I added the AND NOT REMOVE~="ALL" becuase I'm not too sure what will happen if you try to uninstall your product without that there. I think it would show the welcome dialog when you uninstall maybe? You'll have to test it with and without the extra AND on the dialog condition.
I think you should re-evaluate whether or not this is actually what you want to do because this seems kind of a weird behaviour to implement in your installer. It should already know its installed by default.

Answer 2

There are 4 elements that control this behavior
Product Id
Product UpgradeCode
Product Version
MajorUpgrade
If you want your installer to correctly block if it's version is installed (and replace itself if you are installing a new version) then you need those values to look like this
Product Id = * - essentially different each time you build the installer
Product UpgradeCode = Same GUID each time - use uuidgen to generate a guid and hardcode this into your element
Product Version = a Major.Minor.Revision version number set appropriately
<Product Id="*" UpgradeCode="guid" Version="1.0.1"
A MajorUpgrade element exists
<MajorUpgrade AllowSameVersionUpgrades="no" DowngradeErrorMessage="A later version of [ProductName] is already installed. Setup will now exit." />
With those elements set, once 1.0.1 is installed, future attempted installs (even if you have rebuilt the installer) will fail.
Bumping the version number to 1.0.2, rebuilding the installer, and running the install will result in 1.0.1 being uninstalled, and 1.0.2 being installed.
Note that you can set the "AllowSameVersionUpgrades" to "Yes" to allow the same version to be "reinstalled" over the existing one