One problem with the Adobe Flash Player is that it does not detect Firefox Portable by itself. For that reason, if you wish to update it and still maintain the integration between the two problems, you should reinstall the Flash Player altogether. Here are the steps that you should follow. First, make sure you close any window of the Firefox browser. You should, then, download the most recent version of the Adobe Flash Player, as well as install an application called Universal Extractor, which is ultimately necessary for carrying out the process. Afterward, you should use Universal Extractor to obtain the files that compose the AFP install executable, namely installflashplayer.exe. Next, you should copy the flashplayer.xpt and NPSWF32.dll files to these destinations in the Firefox Portable Edition directory:
After this process, your updated Adobe Flash Player should work just fine within Firefox Portable.