I have 2 profiles for Firefox but only one of them has the Firefox adapter installed.
Where can I find the ".xpi" adapter for Mozilla Firefox integration?

Bump....

The latest FDM v3.5RC extension for Firefox v4b11 is now at v1.5.1.
Does anyone have a clue as to where this file can be downloaded?

Look for extensions in user profile.

Usher wrote:Look for extensions in user profile.

The extension is not installed in the user profile, least ways for Fx v4 its not; only the entry "fdm_ffext@freedownloadmanager.org", which points to "C:\Program Files\Free Download Manager\Firefox\Extension", so I think you misunderstood what I was asking for.

I was asking for a link, to download the extension, so it could be reinstalled in Firefox when needed without having to completely reinstall FDM just to get the extension installed, that will not work because it is out of date.
With the extension in hand, it can be modified (or max version can be bumped up) to be compatible with up and coming versions of Firefox. I have done this in the past with incompatible versions of Firefox/FDM.

For Example:
The FDM extension was not compatible with the Fx v4betas, until the 1.5.1 version.
Had I had the extension available to me in the form of an ".xpi" file, I could have modified it to work with the Fx v4betas and not have to revert back to Firefox v3.6.13, when the FDM was needed.

As you well know, the purpose of any beta, is the work out all the incompatibilities of other programs with one another.
Without the FDM extension, the cohesion of the two is impossible to determine.

hapecat® wrote:

Usher wrote:Look for extensions in user profile.

The extension is not installed in the user profile, least ways for Fx v4 its not; only the entry "fdm_ffext@freedownloadmanager.org", which points to "C:\Program Files\Free Download Manager\Firefox\Extension"

And which is OK. The FDM extension is not installed in the user profile directly, but via the file fdm_ffext@freedownloadmanager.org which contains
proper redirection to the real extension location.
If you want FDM to work with Firefox for all users, you should copy this file to the extensions subfolder in the browser folder rather than in the user profile folder.

hapecat® wrote:I was asking for a link, to download the extension, so it could be reinstalled in Firefox when needed without having to completely reinstall FDM just to get the extension installed, that will not work because it is out of date.

FDM extension for Firefox comes with FDM installer and installs in the FDM folder, as you already know. There is no separate installer for that extension.

hapecat® wrote:With the extension in hand, it can be modified(...)

It seems you should learn more about Mozilla extensions. Search for better answers in Mozilla forums, please.