Try this first:

Open the TB profile:

- TB menu > Help > Troubleshooting information

- under the Application Basics section next to Profile Folder, click 'Open folder'

Close TB > rename the handlers.json file in your profile folder to handlers.old > restart TB

When you click a link now, you should be presented with a screen where you can choose which browser to use.

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If that didn't work, try this:

Open the config editor:

- TB menu > Settings > General > scroll all the way down > click the 'Config editor' button

Search for and set these to true:

- network.protocol-handler.warn-external.http

- network.protocol-handler.warn-external.https

When you click a link now, you should be presented with a screen where you can choose which browser to use. Once done, reset the config options to false.

TB uses the operating system's default browser. Set Chrome as the default in Windows Settings, and also in Chrome settings.

Even if the default is set correctly, you might still receive links that aren't clickable, especially if they are sent from mobile mail apps such as on phones, or even from the Windows built-in mail app ('Outlook'). This can happen if the sender enters the URL directly in the message instead of embedding it in text.