Firefox re-allow `alerts`?

Solution 1:

To re-allow alerts in the Firefox website:

  • Enter the website

  • Show website info:

    • If the menu is enabled, click Tools > Page Info
    • If the menu is disabled, press Ctrl+I
  • Click Permissions

  • Next to the "Open pop-up windows" permission, uncheck "Use Default"

  • Click Allow

  • Restart Firefox (for me it didn't work without it).