Local site: Access to 127.0.0.1 was denied HTTP ERROR 403

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1

Description of the issue:

Developing simple flask app on 127.0.0.1:5000 .

When there is a server error, Brave often stops attempts to load the page and instead defaults to:

Access to 127.0.0.1 was denied
You don’t have authorization to view this page.
HTTP ERROR 403

Other browsers (Safari) do not have this issue.

Shields/extensions are off.
Privacy/security settings minimized.

All site cookies and storage are blank, but I clear them anyway with same result.

Restarting the server has no effect — it is as if Brave prevents attempts to connect for an extended period of time, and eventually it allows it again.

Incognito window sometimes (but not always) allows connecting when normal window is 403, but the same effect can be triggered in incognito with a thrown server error too.

How can this issue be reproduced?

  1. Visit local site (127.0.0.1:5000) which is run on flask.
  2. If server route has error, Brave prevents reattempts, even if server code is cleaned up.

Expected result:

Be able to visit minimum working example: the homepage.

Brave Version( check About Brave):

Version 1.75.175 Chromium: 133.0.6943.54 (Official Build) (arm64)

Additional Information:

Same issue reported recently:

2

Example:

This error triggered it:

  File "/Users/kando/vsc/pielection/app/bp/elec/views.py", line 180
    elections_active=elections_active#,
                     ^^^^^^^^^^^^^^^^^^
SyntaxError: invalid syntax. Perhaps you forgot a comma?
3

Deleting cookies browser wide, rather than site wide, appears to resolve it.
How can I prevent the need to delete browser cookies to resolve this?

4

Attempting to visit the site when the server is down and will trigger it and again, the issue will remain when the server is back up.