To whom it may concern...
I found that to run current versions of Firefox - also including ESR and SeaMonkey - the file pdh.dll is missing in \FirefoxPortable\App\Firefox. You will get the following error message: "XPCOM is missing"
As it looks you can use any 32bit pdh.dll as far back as Windows 6 (Vista) - works also on all newer WindowsPE versions including Windows 10 PE or Core.
If you have a 64bit Windows install copy pdh.dll from %windir%\SysWOW64\pdh.dll
Maybe recommended to the maintainer of this Portable App to include the DLL in future releases.
This file is supposed to be included with Windows. It is illegal to distribute it with apps. If your Windows doesn't include it, it's broken.
If you're using a real copy of Windows, run the System File Checker sfc.exe to fix the issue.
If you're running a Windows PE build, contact the builder to fix their bug.
Sometimes, the impossible can become possible, if you're awesome!
The builder is Microsoft as I use the AIK to build my PE - do not trust any PE "Builder" softwares.
However, others now know how to fix it...
Your friendly MSI application packager from next door (-:
If that's the case, it's a pretty bad bug on Microsoft's part. Granted, Windows PE isn't really intended to run regular apps, it's just supposed to be for basic sysadmin stuff. That's why we don't officially support it.
Sometimes, the impossible can become possible, if you're awesome!