Claude Code MAX — Web Fetch returns 401 API Error: “OAuth authentication is currently not supported.”

Bug Description
There is an issue where using the Web Fetch tool while using Claude Code on the MAX plan results in an API Error: 401 {"type":"error","error":{"type":"authentication_error","message":"OAuth authentication is currently not supported."}} and the tool cannot be used

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.0.22
• Feedback ID: b7f325d1-aaa6-438c-a1f4-86f2b5a7c730

Errors

[{"error":"SyntaxError: Unexpected token '/', \"/Users/thk\"... is not valid JSON\n    at JSON.parse (<anonymous>)\n    at file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:62:719\n    at Q (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:8:15093)\n    at gs0.<anonymous> (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3684:219)\n    at gs0.B [as _actionHandler] (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3605:528)\n    at file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3609:3119\n    at gs0._chainOrCall (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3609:1686)\n    at gs0._parseCommand (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3609:3095)\n    at gs0.parseAsync (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3606:4167)\n    at BP8 (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3731:1584)","timestamp":"2025-10-19T04:30:44.856Z"},{"error":"Error: 401 {\"type\":\"error\",\"error\":{\"type\":\"authentication_error\",\"message\":\"OAuth authentication is currently not supported.\"},\"request_id\":\"req_011CUFvuAZ6X1ExYAS6UWYbz\"}\n    at E4.generate (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:203:83082)\n    at Jy.makeStatusError (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:357:2117)\n    at Jy.makeRequest (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:357:5330)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at async BTQ.Ao1.model (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3310:18707)\n    at async Ao1 (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:2650:39781)\n    at async BTQ (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3310:18875)\n    at async file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3310:12822\n    at async ba0 (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3310:4494)\n    at async Nm (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3310:12793)","timestamp":"2025-10-19T04:31:29.546Z"},{"error":"SyntaxError: Expected property name or '}' in JSON at position 1 (line 1 column 2)\n    at JSON.parse (<anonymous>)\n    at file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:62:719\n    at Q (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:8:15093)\n    at zn2 (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:1057:20629)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)","timestamp":"2025-10-19T04:31:29.549Z"},{"error":"Error: 401 {\"type\":\"error\",\"error\":{\"type\":\"authentication_error\",\"message\":\"OAuth authentication is currently not supported.\"},\"request_id\":\"req_011CUFvvBdrsB3UL7n4Zrh21\"}\n    at E4.generate (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:203:83082)\n    at Jy.makeStatusError (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:357:2117)\n    at Jy.makeRequest (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:357:5330)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at async BTQ.Ao1.model (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3310:18707)\n    at async Ao1 (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:2650:39781)\n    at async BTQ (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3310:18875)\n    at async file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3310:12822\n    at async ba0 (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3310:4494)\n    at async Nm (file:///Users/thkt/.claude/local/node_modules/@anthropic-ai/claude-code/cli.js:3310:12793)","tim

Note: Error logs were truncated.