Dreamweaver CS6 will not start

Hi @Graham Laddie,

Use the Adobe Cleaner Tool below to wipe Adobe apps from your system.  Restart your computer.

https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html

Reinstall CS6.  It's on life support but as of this writing it can still be activated with the following:
1. original media (disks or downloads) that you received at purchase and a way to read them,
2. a legitimate serial number for that specific version, language and platform (Win/Mac),
3. an older operating system that can support legacy 32-bit apps.
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NOTE 1 : Creative Suite installers won't work on macOS Sierra, High Sierra or Mojave without terminal workarounds. See the help article below.
https://helpx.adobe.com/creative-cloud/kb/install-creative-suite-mac-os-sierra.html

NOTE 2: Creative Suite is NOT compatible with Catalina or Big Sur.

NOTE 3: Legacy Creative Suite is discontinued & unsupported. Use at your own risk.

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Beware of fake Adobe reps who may contact you privately offering to sell you software or take control of your computer. It's a scam, run away!
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3 Easy Ways to Identify Genuine Adobe Staff
https://tinyurl.com/10791730

What is the exact error you are seeing?

Is your CS6 an upgrade version? (It should say somewhere on the packaging). If it is, you would need the qualifying serial number from the previous version to install it. To get that, all you should need to do is log into your Adobe account to look up registered products.

If you are getting a "License Revoked" message, it would mean you inadvertantly purchased an illegal copy of a volume license from a third party seller in the past and Adobe has finally caught up to the thieves, disabling the volume license.