Cannot update Flash due to missing plugin "application/getplusplusadobe16291"
I have the current version of Firefox and am trying to update Flash Player. The top of the Adobe download page shows missing plugins required to view all the content. When I try to install the missing plugins, they are listed as unknown with the above text. When I try to manually install and open gp.xpi it says it already exists and I say to replace and try to open the download and Adobe Reader says it cannot open because it is unsupported or has been damaged.
Opaite Mbohovái (2)
That plugin is not needed, you can install Flash by using the manual installers, for details see http://kb2.adobe.com/cps/191/tn_19166.html#main_ManualInstaller
As TonyE says you don't need that plugin, it's only a downloader. In fact the solution to the problem is far easier.
To download Adobe Reader X to its latest version you're first directed here
What the problem is is that Firefox has a missing plugin which cannot be installed automatically (the Adobe downloader). So all you have to do is copy and paste the above URL onto your IE browser
Open the page under IE and the download will begin. When it asks you to run, run it and then while the downloader downloads Adobe Air X and the latest Flash as well, make sure you close both IE and Mozilla. Install it and then when you restart Firefox and from add-ons go to the Plugins tab and click Find Updates, you will now see that your installation was successful.
Repeat the same trick for most of the 'missing plugins' issues that Firefox encounters at times; for me, it works every time like a charm ;)