Quando o Firefox congela, pára de responder ao clicar nele e não mostra sinais de estar a funcionar de todo. Também aparece na barra de título a frase "(Não está a responder)" enquanto que o cursor gira como se estive no modo de espera.O cursor também fica em modo de espera quando está sobre a janela do Firefox. Este artigo cobre as variadas soluções, de acordo com a situação em que ocorre.

• Se o Firefox está a usar muitos recursos do computador, veja a solução proposta em Firefox utiliza muitos recursos da CPU - Como corrigir and Firefox utiliza muita memória ou recursos da CPU - Como corrigir.
• Se recebeu um aviso a dizer: Um script não está a responder, veja Aviso "O script não responde" - o que significa e como resolver.
• Se o Firefox foi encerrado de forma inesperada, veja Solucionar problemas de craches no Firefox (fechando ou saindo inesperadamente).

Para resolver problemas deste género, que não estão especificamente mencionados neste artigo, veja Identificar e diagnosticar problemas do Firefox.

Firefox hangs at random times

If Firefox seems to hang randomly and not after a specific action (for example, downloading a file or quitting Firefox), try the solutions in this section.

Create a new places database

If hangs are periodic, it may be caused by a corrupted places database. To create a new places database, do the following:

1. O modelo "ProfileFolder" não existe ou não possui uma revisão aprovada.
2. Clique no ícone Menu do Firefox e selecione Sair.Clique no ícone do menu do Firefox no topo do ecrã e selecione Sair do Firefox.Clique no menu Firefox e selecione Sair. Wait until Firefox has completely quit.
3. In the Firefox profile folder, find and rename the files places.sqlite and places.sqlite-journal (if it exists).
   • To rename a file, right-click on it and select rename from the menuclick on it once to select it and then click a second time on the file name to make it editable. Then add .old to the end of its name.
4. Finally, reopen Firefox.
   • When Firefox reopens it will create a new places database. Your browsing history will be lost but Firefox will automatically import your bookmarks from the most recent backup file.

Turn off hardware acceleration

With some graphics card and graphics driver setups, Firefox may hang when using hardware acceleration. You can try turning off hardware acceleration to see if it fixes the problem.

1. Na barra do "Menu" no topo do ecrã, clique em Firefox e selecione Definições (selecione Preferências nas versões mais antigas do macOS).Clique no botão Menu e selecione Definições.
2. Select the Advanced panel and the General tab.
3. Uncheck Use hardware acceleration when available.
4. Clique no ícone Menu do Firefox e selecione Sair.Clique no ícone do menu do Firefox no topo do ecrã e selecione Sair do Firefox.Clique no menu Firefox e selecione Sair.
5. Start Firefox the way you normally do.

If the problem is no longer happening, then hardware acceleration was likely the cause. You can try updating your graphics drivers to see if that fixes it or simply run without hardware acceleration.

Troubleshoot your plugins

Sites that use plugins such as Java, Adobe Reader, or Flash can cause Firefox to hang. For information on troubleshooting plugins and on determining whether a plugin is causing your problem, see the Solucionar problemas com plug-ins, tais como Flash ou Java para corrigir problemas comuns do Firefox article.

Delete duplicated Session Restore files

Firefox may be slow to respond or hang if multiple copies of its Session Restore file have been created:

1. Abra a sua pasta de perfil:

   • Clique no botão Menu, clique em Ajuda e depois em Mais informação para diagnóstico de problemas Será aberto o separador da Informação para resolução de problemas.
   • Na secção de Informações básicas da aplicação Ao lado de: "Pasta de PerfilDiretoria Perfil", clique em Abrir pastaMostrar no FinderAbrir Diretoria. Será apresentada uma janela com a sua pasta de perfil.Será aberta a sua pasta de perfil.Será aberta a diretoria de perfil.
   Nota: Se o Firefox exibe um erro depois de clicar em Abrir pasta ou se não conseguir abrir ou utilizar o Firefox, siga as instruções em Encontrar o seu perfil sem abrir o Firefox.

2. Clique no ícone Menu do Firefox e selecione Sair.Clique no ícone do menu do Firefox no topo do ecrã e selecione Sair do Firefox.Clique no menu Firefox e selecione Sair.
3. Locate and delete the sessionstore.js file and any copies, such as sessionstore-1.js, sessionstore-2.js.

Change the PAC implementation

If you're using a proxy auto-config file (PAC), Firefox may hang when you attempt to load sites that don't exist or that you haven't opened recently. To determine if you use an automatic proxy configuration file:

1. Na barra do "Menu" no topo do ecrã, clique em Firefox e selecione Definições (selecione Preferências nas versões mais antigas do macOS).Clique no botão Menu e selecione Definições.
2. Click the Advanced icon.
3. Click the Network tab.
4. Click Settings. The Connection Settings dialog appears.
5. If Automatic proxy configuration URL is selected, you are using an automatic proxy configuration file. Do not disable this setting, which will prevent you from accessing the Internet. Instead, provide this workaround to your network administrator.
6. Click Cancel.

Firefox hangs while playing Flash videos

See Playing Flash videos makes Firefox hang.

Firefox hangs after using it for a long time

Update Firefox

The latest Firefox versions includes improvements in memory usage, especially during long sessions. Update Firefox to the latest version.

Restart Firefox

Firefox may hang if left open for long periods of time. To fix the issue, restart Firefox.

If you regularly leave Firefox open so that you return to where you left off, you may want to use Firefox's Session Restore feature. For more information, see Configuring session restore.

Firefox hangs while loading the first window

Speed up Session Restore

If you have many tabs to restore, Firefox may hang while loading those sites. Make sure to check Don't load tabs until selected in the Tabs panel of the OptionsPreferences windowGeneral panel of the OptionsPreferences window so that only the last selected tab is loaded at startup. Try to use Tab Groups so that only websites in the visible tab group load first.

Firefox hangs when downloading files or saving images

If Firefox hangs when you attempt to download a file or save an image, try these solutions:

Clear download history

Firefox may hang when downloading files if your download history has grown too large. To clear the download history:

1. At the top of the Firefox window, click on the Firefox button (Tools menu in Windows XP), and then click DownloadsOn the menu bar, click on the Tools menu, and then click DownloadsAt the top of the Firefox window, click on the Tools menu, and then click Downloads. The Downloads window will open.
2. Click Clear List. The download history is cleared.
3. Download some sample files to see if the hanging has stopped.

Choose a different download folder

Firefox may hang if the last download folder location (e.g. a shared volume or USB drive) is no longer available. To fix this:

1. Na barra do "Menu" no topo do ecrã, clique em Firefox e selecione Definições (selecione Preferências nas versões mais antigas do macOS).Clique no botão Menu e selecione Definições.
2. Select the General panel.
3. In the Downloads pane, select Save files to and click the Browse button.
4. In the Browse For Folder window, choose a new folder location.
5. Feche a página das Definições. Quaisquer alterações efetuadas serão guardadas automaticamente.

See if you are now able to download files or save images. If this works, you can go back to your Firefox settings, if you wish, and select Always ask me where to save my files.

Disable virus scan in Firefox preferences

With some antivirus programs, the virus scan that Firefox starts after files are downloaded may cause Firefox to hang. You can disable virus scanning with the following steps (this will not disable your antivirus program):

1. Digite about:config na barra de endereço e pressione EnterReturn.
   Poderá aparecer uma página de aviso. Clique em Aceitar o risco e continuar para ir para a página de about:config.
2. Locate the browser.download.manager.scanWhenDone preference and double click it to change the value to false.

Firefox hangs when you quit it

Sometimes when you close Firefox, it may stop responding and remain in memory, even though no Firefox windows are open. This can prevent Firefox from working properly the next time you open it or you may see a "Close Firefox" dialog box with the message, Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system.. You must then end all Firefox processes or restart the computer before you can reopen Firefox (see Erro "O Firefox já está em execução, mas não está a responder' - Como corrigir for other causes and solutions).

Close Firefox completely

1. Clique no ícone Menu do Firefox e selecione Sair.Clique no ícone do menu do Firefox no topo do ecrã e selecione Sair do Firefox.Clique no menu Firefox e selecione Sair.
2. Close any remaining dialog boxes or secondary windows such as the Downloads window.

If Firefox processes that remain in memory at exit are a recurring problem, try the following solutions.

Troubleshoot your extensions

A problematic extension can cause the problem, which can be resolved by disabling or uninstalling the extension. For information on diagnosing and fixing problems caused by faulty extensions, see the Resolução de problemas para extensões, temas e aceleração por "hardware" para resolver problemas comuns do Firefox article.

Update or disable the Java plugin

Sometimes Java applets can cause the Firefox process to persist after exit. Try updating Java to the latest version by going to Mozilla's plugin check page or, if you don't need the Java plugin, you can disable it from the Plugins panel of the Firefox Add-ons Manager. For more information, see Utilizar o plugin Java para visualizar conteúdo interactivo em websites.

Based on information from Firefox hangs (mozillaZine KB)