Installation failed because a newer version of the extension is installed.

[richgartland]

Hi, I'm installing my extension on a Windows 7 setup, where I have InDesign CC versions (2014, 2015, 2017) installed. I've removed all previous versions of my extension, but ZXPInstaller keeps giving me this message. Maybe I've missed something... I've removed files from these places:

• "%HOMEPATH%\AppData\Local\Temp\cep_cache*.*"
• C:\Program files (x86)\Common files\Adobe\CEP\extensions
• Plus InDesign prefs and saveddata
  At this point the error message seems spurious, like it's really some other error instead. Ideas?
  BTW, I too am very grateful for this app -- it's a lifesaver for us.

[cameronmcefee]

You could also try C:\Users\<USERNAME>\Program Files\Common Files\Adobe\<CEP>\extensions. I've seen some issues with files getting installed there unexpectedly.

Other than that, your spurious suspicion might not be too far off. Some times the Extension Manager conflicts with ZXPInstaller (which uses Adobe's ExMan cli under the hood). You can also try removing the Extension Manager using the official uninstaller, which should theoretically clean up its internal registry that might be causing false conflicts.

[richgartland]

Sigh... uninstalling failed and it suggests I use the cleaner tool, which I am loathe to do for fear it's going to leave me with other things uninstalled.

[richgartland]

Ok was able to uninstall using the Creative Cloud app, though I still see the same behavior in ZXPInstaller.

[cameronmcefee]

What's the actual error you're getting?

Full discloser, I'm just guessing with this stuff. Since ZXPInstaller uses an Adobe CLI to do all it's work, we're at the mercy of its quirks.

[richgartland]

The title of this post is an exact rendering of the error message.

[cameronmcefee]

Ah, whoops, sorry. Oh I forgot, you mentioned looking in the CEP folder for your extension, which is CC 2014+. Did you check CEPServiceManager4 (CC)?

There's also a difference between User and System install. I forget which ones are which but here are the locations:
C:\Users\<USERNAME>\AppData\Roaming\Adobe\<CEPFOLDER>\extensions
C:\Users\<USERNAME>\Program Files (x86)\Common Files\Adobe\<CEP>\extensions
C:\Users\<USERNAME>\Program Files\Common Files\Adobe\<CEP>\extensions

If I were in your shoes, this is what I'd do:

• Full system search (including system/hidden folders) for a file or folder in the extension, assuming I know the name of it. Delete anything I find. Restart all Adobe apps in which it should launch and check that it is gone. If the installation fails at this point, it's probably an Adobe error…

• Adobe extension installers use a sort of central manifest to manage keeping track of what is and isn't installed. It can be corrupted or do strange things. I unfortunately don't know where this is stored off the top of my head, but removing that manifest (typically uninstalling the Extension Manager does the trick) resets it and the problem goes way if it's a corruption issue. You can try googling things like "Where is Extension Manager data/database/preferences stored".