Browser tool navigate consistently fails with "denied or failed" for previously-working sites

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

I'm using Claude Code with the Browser tool (mcp__Claude_Browser__navigate) on a Windows VPS. For most of a session, navigation to a specific site (mql5.com) worked fine — I was able to browse, log in, read pages, fill forms, etc. Then, mid-session, every subsequent navigate call to the same site (and others) started failing with a generic error: "navigation to https://mql5.com was denied or failed."

• No error details are given beyond "denied or failed."
• The browser tab appears to open (about:blank) but never actually loads the target URL.
• Retrying the same navigate call repeatedly does not help.
• This is not a per-site block — it previously worked fine on the exact same URL earlier in the same session.
• This has happened on at least two separate occasions (days apart), each time lasting the rest of that session, then resolving on its own by the next session — suggesting an intermittent backend/infrastructure issue rather than a site-specific block or a persistent bug.

What Should Happen?

The navigate call should either succeed and load the requested URL, or return an error with enough detail to tell whether the failure is a network issue, a site-side block, or a tool-side problem — so it's possible to distinguish a transient outage from something that needs a different fix.

Error Messages/Logs

navigation to https://mql5.com was denied or failed

Steps to Reproduce

1. In an interactive Claude Code session, use the Browser tool (mcp__Claude_Browser__navigate) to open a URL that has never been visited before in that session (e.g. preview_start with a URL).
2. Browse normally for a while — navigate, read_page, form_input, computer clicks all work fine, including repeated navigation to the same domain.
3. At some point mid-session (not tied to any specific action taken), a navigate call to a URL that worked moments earlier starts failing with "navigation to <url> was denied or failed."
4. Retry the same navigate call multiple times. Still fails, same error, no additional detail.
5. Try navigate to a different, unrelated domain in the same tab. Also fails with the same generic error.
6. The failure persists for the rest of that session. In a later, separate session, the same tool works normally again against the same site with no changes made.

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.32352.1

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_