Why can I log in to the website, but not SourceTree?

[LynnCo AppSupport]

I cannot log in to SourceTree using my BitBucket or Atlassian account. I can immediately switch to a web browser on the same machine and connect to both, but neither will let me connect via SourceTree.

Atlassian says : "Something went wrong while attempting to validate your credentials."

BitBucket says "Invalid URI: The hostname could not be parsed."

I'm trying to connect directly as I don't have a Google account.

[Ana Retamal]

Hi, welcome to the Community! We'll need more information to narrow this issue down and help you solve it, can you answer the following:

1. Are you using Windows or Mac?
2. If Windows, is Internet Explorer updated to the latest version? 
3. Which Sourcetree version are you using?
4. Are you using Bitbucket Cloud or Server?
5. Can you send a screenshot of the error you get?

Kind regards!

Ana