Firefox 40.0 and 40.0.2 are 32-bit programs, so they would use the 32-bit version of Flash. The same installer should install both, however, so you shouldn't need an additional download. Could you check that Flash is not disabled on the Add-ons page? Either: * Ctrl+Shift+a * "3-bar" menu button (or Tools menu) > Add-ons In the left column, click Plugins. Scroll to the end and check for "Shockwave Flash" and if found, change "Never Activate" to either "Always Activate" or "Ask to Activate". ---- If Flash is not listed, could you verify the physical presence of the plugin(s): ''32-bit Firefox:'' Folder: C:\Windows\SysWOW64\Macromed\Flash File: '''NPSWF32_18_0_0_209.dll''' ''64-bit Firefox (only beta/developer/nightly):'' Folder: C:\Windows\system32\Macromed\Flash File: '''NPSWF64_18_0_0_209.dll''' If it is missing: open [https://www.adobe.com/products/flashplayer/distribution3.html] and in the first table, look for the row for "plugin-based browsers" and you can use either the EXE or the MSI installer. ---- If that checks out: '''Confirm that Firefox is scanning the registry for plugins''' Firefox finds most plugins from a registry entry. Some users have the scanning turned off for some reason. Here's how to check and fix that: (1) In a new tab, type or paste <strong>about:config</strong> in the address bar and press Enter. Click the button promising to be careful. (2) In the search box above the list, type or paste <strong>scan</strong> and pause while the list is filtered (3) If <strong>plugin.scan.plid.all</strong> is not set to its default value of true, double-click it to toggle it back to the default. ''If you changed this setting, exit and restart Firefox to trigger another scan.'' If you check the Add-ons page, Plugins section again, can you find Shockwave Flash there, either enabled or at the bottom disabled? ---- ''If Firefox is set to scan but still does not find the plugin and list it on the Add-ons page...'' '''Remove Firefox's plugin registry file''' Sometimes the pluginreg.dat file becomes corrupted. You can remove it and have Firefox re-scan for plugins. Open your current Firefox settings (AKA Firefox profile) folder using either * "3-bar" menu button > "?" button > Troubleshooting Information * Help menu > Troubleshooting Information * type or paste '''about:support''' in the address bar and press Enter In the first table on the page, click the "Show Folder" button to launch a new Windows Explorer window showing your settings files. Leaving that window open, switch back to Firefox and Exit, either: * "3-bar" menu button > "power" button * File menu > Exit Pause while Firefox finishes its cleanup, then rename '''pluginreg.dat''' to something like pluginreg.old Start Firefox back up again. (If you want to restore your previous non-private session, use History &gt; Restore Previous Session.) When you return to the Add-ons page, is Flash finally there?