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Firefox-Class not registered error

Posted

I tried changing default browser to IE and then back to firefox and nothing changed. Also I tried reinstalling firefox and it fixed error for a day but now its back. I can open firefox with Run->firefox.exe and right clicking on icon in taskbar and selectiong new tab. Also I scanned PC for viruses and nothing was found. Biggest issue firefox no longer opens when I click on links, so I had to change default browser to IE.

I tried changing default browser to IE and then back to firefox and nothing changed. Also I tried reinstalling firefox and it fixed error for a day but now its back. I can open firefox with Run->firefox.exe and right clicking on icon in taskbar and selectiong new tab. Also I scanned PC for viruses and nothing was found. Biggest issue firefox no longer opens when I click on links, so I had to change default browser to IE.

Additional System Details

Installed Plug-ins

  • Shockwave Flash 12.0 r0

Application

  • Firefox 30.0a2
  • User Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:30.0) Gecko/20100101 Firefox/30.0
  • Support URL: https://support.mozilla.org/1/firefox/30.0a2/WINNT/en-US/

Extensions

  • Adblock Plus 2.5.1 ({d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d})
  • Cryptocat 2.1.21 (cryptocat@crypto.cat)
  • HTTPS-Everywhere 3.4.5 (https-everywhere@eff.org)
  • NoScript 2.6.8.19rc2 ({73a6fe31-595d-460b-a920-fcc0f8843232})
  • Troubleshooter 1.1a (troubleshooter@mozilla.org)

Javascript

  • incrementalGCEnabled: True

Graphics

  • adapterDescription: Intel(R) HD Graphics
  • adapterDescription2:
  • adapterDeviceID: 0x0106
  • adapterDeviceID2:
  • adapterDrivers: igdumd64 igd10umd64 igd10umd64 igdumd32 igd10umd32 igd10umd32
  • adapterDrivers2:
  • adapterRAM: Unknown
  • adapterRAM2:
  • adapterVendorID: 0x8086
  • adapterVendorID2:
  • direct2DEnabled: True
  • directWriteEnabled: True
  • directWriteVersion: 6.3.9600.16384
  • driverDate: 1-29-2014
  • driverDate2:
  • driverVersion: 9.17.10.3347
  • driverVersion2:
  • info: {u'AzureCanvasBackend': u'direct2d', u'AzureFallbackCanvasBackend': u'cairo', u'AzureContentBackend': u'direct2d', u'AzureSkiaAccelerated': 0}
  • isGPU2Active: False
  • numAcceleratedWindows: 1
  • numTotalWindows: 1
  • webglRenderer: Google Inc. -- ANGLE (Intel(R) HD Graphics Direct3D9Ex vs_3_0 ps_3_0)
  • windowLayerManagerRemote: False
  • windowLayerManagerType: Direct3D 10

Modified Preferences

  • accessibility.typeaheadfind.flashBar: 0
  • browser.cache.disk.capacity: 358400
  • browser.cache.disk.smart_size.first_run: False
  • browser.cache.disk.smart_size.use_old_max: False
  • browser.cache.disk.smart_size_cached_value: 358400
  • browser.places.smartBookmarksVersion: 7
  • browser.sessionstore.upgradeBackup.latestBuildID: 20140330004001
  • browser.startup.homepage_override.buildID: 20140330004001
  • browser.startup.homepage_override.mstone: 30.0a2
  • browser.tabs.warnOnClose: False
  • dom.mozApps.used: True
  • extensions.lastAppVersion: 30.0a2
  • font.internaluseonly.changed: False
  • gfx.direct3d.last_used_feature_level_idx: 0
  • network.cookie.lifetimePolicy: 2
  • network.cookie.prefsMigrated: True
  • places.database.lastMaintenance: 1396210211
  • places.history.expiration.transient_current_max_pages: 104710
  • plugin.disable_full_page_plugin_for_types: application/pdf
  • plugin.importedState: True
  • plugin.state.flash: 1
  • plugin.state.npadobeaamdetect: 0
  • plugin.state.npmeetingjoinpluginoc: 0
  • plugin.state.nppandowebplugin: 1
  • plugin.state.nppdf: 0
  • plugin.state.npspwrap: 0
  • privacy.donottrackheader.enabled: True
  • privacy.sanitize.migrateFx3Prefs: True
  • privacy.sanitize.timeSpan: 2
  • storage.vacuum.last.index: 1
  • storage.vacuum.last.places.sqlite: 1395592194

Misc

  • User JS: No
  • Accessibility: No
AliceWyman
  • Moderator
240 solutions 2597 answers

Related bug (read Bugzilla etiquette before commenting in bug reports)

  • Bug 982478 - updating from fxmetro will produce "Class not registered" error prompt

Try uninstalling Firefox 30.0a2 (Aurora) - see Uninstall Firefox from your computer - but DO NOT select the option to remove your personal data and customizations since doing so will remove your bookmarks, saved passwords, and other data. (As a precaution, make a backup copy of your Firefox profile folder).

You can then reinstall Firefox by downloading it again from either www.mozilla.org for the latest release version (Firefox 28) or download the installer from http://www.mozilla.org/firefox/channel/#aurora if you want to continue testing the Aurora build.

Related bug (read [https://bugzilla.mozilla.org/page.cgi?id=etiquette.html Bugzilla etiquette] before commenting in bug reports) *[https://bugzilla.mozilla.org/show_bug.cgi?id=982478 Bug 982478] - updating from fxmetro will produce "Class not registered" error prompt Try uninstalling Firefox 30.0a2 (Aurora) - see [[Uninstall Firefox from your computer]] - but DO NOT select the option to remove your personal data and customizations since doing so will remove your bookmarks, saved passwords, and other data. (As a precaution, make a backup copy of your [/kb/profiles-where-firefox-stores-user-data Firefox profile folder]). You can then reinstall Firefox by downloading it again from either www.mozilla.org for the latest release version (Firefox 28) or download the installer from http://www.mozilla.org/firefox/channel/#aurora if you want to continue testing the Aurora build.