See: https://support.mozilla.com/en-US/kb/unable+to+install+add-ons#Download_Error_228 http://support.mozilla.com/tiki-view_forum_thread.php?locale=sk&comments_parentId=471049&forumId=1#threadId687367

You do NOT need getplus (the Adobe DLM or Download Manager) to get Adobe Flash (aka Shockwave Flash). It gets installed when you click that "Allow" button on the Adobe site; it downloads getplus and getplus, in turn, is suppose to download Flash, but it causes problems for a lot of users. Follow the instructions below instead to get Flash without getplus. To rid yourself of getplus, see if any of these suggestions works for you: http://secunia.com/community/forum/thread/show/3665/adobe_dlm_will_not_uninstall

Install/Update Adobe Flash Player for Firefox (aka Shockwave Flash): your ver. 10.0 r22; current ver. 10.1 r53 (important security update 2010-06-10) ~~red:Check your version here~~: http://www.mozilla.com/en-US/plugincheck/ See: Updating Flash -use Firefox to download and SAVE to your hard drive (save to Desktop for easy access) -exit Firefox (File > Exit) -check to see that Firefox is completely closed (Ctrl+Alt+Del, choose Task Manager, click Processes tab, if "firefox.exe" is on the list, right-click "firefox.exe" and choose End process, close the Task Manager window) -double-click on the Adobe Flash installer you just downloaded to install/update Adobe Flash -when the Flash installation is complete, start Firefox, and test the Flash installation here: http://kb.adobe.com/selfservice/viewContent.do?externalId=tn_15507&sliceId=1

• NOTE: On Vista and Windows 7 you may need to run the plugin installer as Administrator by starting the installer via the right-click context menu if you do not get an UAC prompt to ask for permission to continue (i.e nothing seems to happen). See this: http://vistasupport.mvps.org/run_as_administrator.htm
• NOTE for IE: Firefox and most other browsers use a Plugin. IE uses an ActiveX version of Flash. To install/update the IE ActiveX Adobe Flash Player, same instructions as above, except use IE to download the ActiveX Flash installer.
• Also see: http://kb.mozillazine.org/Flash ~~red:AND~~ How do I edit options to add Adobe to the list of allowed sites

Other Issues: ~~red:You have installed plug-ins with known security issues. You should update them immediately.~~

Update Java: your ver. 1.6.0.17; current ver. 1.6.0.20 (important security update 04-15-2010) (Firefox 3.6 and above requires Java 1.6.0.10 and above; see: http://support.mozilla.com/en-US/kb/Java-related+issues#Java_does_not_work_in_Firefox_3_6 ) (Windows users: Do the manual update; very easy.) ~~red:Check your version here~~: http://www.mozilla.com/en-US/plugincheck/ See: Updating Java Do the update with Firefox closed.

I don't get an "allow" button, that's my problem. I get a prompt to d/l gp.xpi which I then try to run with Firefox but nothing happens. It's a loop I can't get out of.

You do not need to download and install the Adobe Download Manager (GetPlus).

You can find the links to download the Flash plugin for Windows at the bottom of this page:

Adobe - Common Flash Player download and installation issues (Windows): http://www.adobe.com/products/flashplayer/support/index.html

Go to: 3. Download Adobe Flash Player

I'm having the same problem with this, only it happens with all add ons. I get error -228 when I try, every time.

I can't install through the add-on manager, from the add on site, or by saving the link on the site. I've tried downloading it in Firefox, Chrome, and IE to no avail.

I can, however, drag existing .xpi files into the add on manager and they will install just fine.

I've looked through all the available other documentation, including the two links suggested by TXGuy above and none of it has helped.

Firefox 3.6.10 wont install Adobe Flashplayer plugin, error -228. Updated Firefox to 3.6.11. Firefox 3.6.11, same problem installing Adobe Flashplayer plugin, error 228.

Tried al hint/tips, still the same error.

Firefox 3.6.10 wont install Adobe Flashplayer plugin, error -228. Updated Firefox to 3.6.11. Firefox 3.6.11, same problem installing Adobe Flashplayer plugin, error 228.

Tried al hints/tips, still the same error.

i get the -228 error all the time when trying this add thing of firefox, i used manuals on the internet with all possible causes and solutions on the error but didn't find how to fix it