New chat creation fails with Invalid request: AbsolutePathBuf deserialized without a base path (existing tasks work)
Environment
OS: Windows 11
VS Code Codex extension: openai.chatgpt-26.513.21555-win32-x64 (latest as of 2026-05-18)
Codex CLI: @openai/codex installed globally via npm, also up to date
Account: ChatGPT-authenticated (Business plan)
What happens
Opening the Codex panel and trying to start a new chat immediately shows a red banner: Error starting chat — Invalid request: AbsolutePathBuf deserialized without a base path. Continuing an existing task from the task list works correctly and returns proper GPT-5.5 responses, so auth/network/model routing are fine. Only the new-chat creation code path fails.
What we already ruled out
No [agents.*] blocks in ~/.codex/config.toml (so not #19257 / #19261)
No ~/.codex/agents/ folder
No project-level .codex/config.toml
Not the WSL agent mode (running Windows-native, sandbox = "unelevated") — so not #16815
Stripping \\?\ Windows long-path prefixes from [marketplaces.*] source lines does not help; restored after testing.
Reload Window can transiently clear the symptom but it recurs on next chat creation.
Notes
Symptom is similar to #19257 and #16815 but neither root cause applies. Looks like another AbsolutePathBuf deserialization site missing an AbsolutePathBufGuard, this time on the new-chat creation path rather than agent role config.
Config (sanitised)
tomlmodel = "gpt-5.5"
model_reasoning_effort = "high"
[windows]
sandbox = "unelevated"
8x [projects.*] blocks (all absolute paths, mixed-case drive letter)
[marketplaces.openai-bundled]
source = '\\?\C:\Users\<user>\.codex\.tmp\bundled-marketplaces\openai-bundled'
[marketplaces.openai-primary-runtime]
source = '\\?\C:\Users\<user>\.cache\codex-runtimes\codex-primary-runtime\plugins\openai-primary-runtime'
5 Comments
Exactly the same issue. Continuing the chat works perfectly, starting a new one fails.
However, I have a bit different setup.
Environment
Laptop:
OS: Linux Ubuntu 20.04
Codex Version: codex-cli 0.141.0
Codex VS Code Plugin Version: v26.616.71553
PC:
OS: Windows 11 Pro
Codex Version: None
Codex VS Code Plugin Version: None
Error itself
I am connected from my laptop to pc's VS code server via SSH (Remote-SSH VS code extension). Codex Extension is enabled locally on laptop.
With that setup, I can not create a new chat. Error: Invalid request: AbsolutePathBuf deserialized without a base path.
However, when I just use the VS code without connection to remote server, new chat successfully gets created.
the same issue,
local is normal,
vs code ssh :Error: Invalid request: AbsolutePathBuf deserialized without a base path.
Same here, happened when I switched to start using WSL in both available options in Codex. Then tried to keep chatting in an existing task
Windows 11 25H2
Chat GPT App
<img width="461" height="57" alt="Image" src="https://github.com/user-attachments/assets/e7521e59-72a0-46fd-a00f-1141c2614a5f" />
Same problem, happened when I use the ssh remote vscode, it shows Error: Invalid request: AbsolutePathBuf deserialized without a base path.
We are still seeing this issue with newer versions:
Behavior:
Error shown:
Error creating chat Invalid request: AbsolutePathBuf deserialized without a base path
Relevant logs:
2026-08-20 09:02:07 [error] Error fetching httpStatus=403 statusText=Forbidden url=/settings/user
2026-08-20 09:02:08 [warning] sa_server_request_failed attachAuth=false routePattern=/settings/user status=403 url=/settings/user
2026-08-20 09:02:14 [error] Request failed conversationId=none error={"code":-32600,"message":"Invalid request: AbsolutePathBuf deserialized without a base path"} failureReason=invalid_config method=thread/start
2026-08-20 09:02:15 [error] Request failed conversationId=none error={"code":-32600,"message":"Invalid request: AbsolutePathBuf deserialized without a base path"} failureReason=invalid_config method=plugin/installed
Additional observation:
Creating a new branch from an existing Codex chat works successfully.
This suggests the issue may be specific to creating a completely new/root chat
rather than all session creation paths. Existing chats can continue, and
branching/forking from an existing chat appears to bypass the failing path.