InstallAware

We have recently upgraded from InstallAware Studio 6.31 to 10.10.

Since then, on some systems the installer fails with:

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Native Engine/Windows Installer Error Notification
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The following error occured while applying changes to system:
Another version of this product is already installed. Installation of this version cannot continue. To configure or remove the existing version of this product, use Add/Remove Programs on the Control Panel

Please review your installation commands.
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(This detailed error text is from a debug build, the release build just shows "Error", without any further details)

It can be fixed by using the Windows Installer Clean Up tool to removing our software from the list.
We would hate to have our customers employ this method.
The installer's sources are unchanged, and everything has been working flawlessly until now.

Can anyone shed some light on this?

Going from 6 to 11 is indeed a steep change, so I would try maybe running the cleanup tools from within your setup.
You can invoke the tools using the Run Program command. Please let me know if you have any other questions.

Thanks, but shipping something like MsiZap is not ok.

Anyway.. Just changed the UpgradeCode to something else, and it's fixed now... Luckily we weren't using patches.