[Error] [UriError]: cannot call joinPath on URI without path — workspacePluginSettingsService

[vs-code-engineering]

Error Message

unhandlederror-[UriError]: cannot call joinPath on URI without path

Stack Trace

    at a.joinPath (./src/vs/base/common/uri.ts:362:9)
    at ele.joinPath (./src/vs/base/common/resources.ts:186:13)
    at joinPath (./src/vs/workbench/contrib/chat/common/plugins/workspacePluginSettingsService.ts:190:65)
    at nR._getValue (./src/vs/workbench/contrib/chat/common/plugins/workspacePluginSettingsService.ts:190:56)
    at cye.handleEvent [as value] (./src/vs/base/common/observableInternal/observables/observableFromEvent.ts:99:24)
    at E._deliver (./src/vs/base/common/event.ts:1354:12)
    at E._deliverQueue (./src/vs/base/common/event.ts:1365:8)
    at E.fire (./src/vs/base/common/event.ts:1389:8)
    at pXt._doUpdateFolders (./src/vs/sessions/services/workspace/browser/workspaceContextService.ts:163:36)

Raw Stack Trace (minified)

Error: [UriError]: cannot call joinPath on URI without path     at a.joinPath (out/vs/sessions/sessions.desktop.main.js:406:59221)     at ele.joinPath (out/vs/sessions/sessions.desktop.main.js:406:68517)     at out/vs/sessions/sessions.desktop.main.js:2855:16977     at Array.map (<anonymous>)     at nR._getValue (out/vs/sessions/sessions.desktop.main.js:2855:16970)     at cye.handleEvent [as value] (out/vs/sessions/sessions.desktop.main.js:407:18574)     at E._deliver (out/vs/sessions/sessions.desktop.main.js:405:3066)     at E._deliverQueue (out/vs/sessions/sessions.desktop.main.js:405:3155)     at E.fire (out/vs/sessions/sessions.desktop.main.js:405:3490)     at pXt._doUpdateFolders (out/vs/sessions/sessions.desktop.main.js:4549:2992)

Details

Property	Value
Bucket ID	4965fca6-65a2-f103-469d-84dd1dd885ba
Version	1.115.0-insider
Commit	41dd792b
Last Seen	Tue Apr 14 2026 17:59:52 GMT+0000 (Coordinated Universal Time)
Platforms	Windows, Linux, Mac
Product	Agents

---

This issue was automatically created from the VS Code Errors Dashboard

[vs-code-engineering]

🔍 Error Investigation

Summary

The WorkspaceSettingsReader in workspacePluginSettingsService.ts calls joinPath(f.uri, configFolder) on every workspace folder URI whenever workspace folders change, but does not guard against folders whose URIs have no path component. When a session's workspace contains a repository or worktree URI without a path (e.g., a URI with only a scheme and authority), URI.joinPath throws [UriError]: cannot call joinPath on URI without path. This affects the Agents product across all platforms, with 3,470 total hits / 1,443 users spanning versions 1.114 through 1.116.

Culprit Commit

Field	Value
Commit	342a781
Author	@connor4312
PR	#300585
Message	plugins: initial support for workspace plugins
Why	Introduced WorkspaceSettingsReader which unconditionally calls joinPath on all workspace folder URIs without validating that the URI has a path. The error has been present since this file was first added (merged March 11, milestone 1.112.0).

Code Flow

sequenceDiagram
    participant WFM as WorkspaceFolderManagement
    participant WCS as SessionsWorkspaceContextService
    participant OBS as observableFromEvent
    participant WSR as WorkspaceSettingsReader
    participant URI as URI.joinPath

    WFM->>WCS: addFolders([{uri: pathlessUri}])
    WCS->>WCS: _doUpdateFolders()
    Note over WCS: Creates WorkspaceFolder<br/>with URI lacking path
    WCS->>OBS: fire(onDidChangeWorkspaceFolders)
    OBS->>WSR: getValue() callback
    WSR->>URI: joinPath(f.uri, ".claude")
    Note over URI: ⚠️ Root cause:<br/>f.uri.path is empty string
    URI->>URI: 💥 throw Error("[UriError]:<br/>cannot call joinPath on<br/>URI without path")
```

### Affected Files

| File | Role |
|------|------|
| `src/vs/workbench/contrib/chat/common/plugins/workspacePluginSettingsService.ts` | **Root cause** — line 190: unguarded `joinPath` in observable callback |
| `src/vs/sessions/services/workspace/browser/workspaceContextService.ts` | **Trigger** — line 163: fires `onDidChangeWorkspaceFolders` without validating folder URIs have paths |
| `src/vs/sessions/contrib/workspace/browser/workspaceFolderManagement.ts` | **Data producer** — provides workspace folder URIs from session data |
| `src/vs/base/common/uri.ts` | **Crash site** — line 362: `joinPath` throws when `uri.path` is falsy |

### Repro Steps

1. Open the VS Code Agents product (vscode.dev with agents enabled)
2. Start or switch to a session whose workspace includes a repository URI without a path component (e.g., a URI with only scheme + authority, or a session that hasn't fully resolved its workspace folder path)
3. The `WorkspaceFolderManagement` contribution adds this folder to the workspace context
4. The `WorkspaceSettingsReader` observable reacts and attempts to `joinPath` on the pathless URI
5. The error is thrown as an unhandled error from the observable callback

> **Note**: The exact workspace configuration that produces a pathless URI depends on the session provider and its data. The error is cross-platform (Windows, Linux, Mac) and affects ~1,400 unique users, suggesting it occurs under relatively common workspace configurations.

### Fix Proposal

**Fix location**: `src/vs/workbench/contrib/chat/common/plugins/workspacePluginSettingsService.ts` → `WorkspaceSettingsReader` constructor (line 190)

**Approach**: Filter out workspace folders whose URIs have no path before calling `joinPath`. Change the `observableFromEvent` callback from:
```
folders.map(f => joinPath(f.uri, configFolder))
```
to:
```
folders.filter(f => f.uri.path).map(f => joinPath(f.uri, configFolder))

Loading

Alternatively (defense in depth), also add a guard in SessionsWorkspaceContextService._doUpdateFolders to skip or normalize workspace folders whose URIs lack a path, preventing the invalid state from propagating to all downstream observers.

Recommended Owner

@connor4312 — author of workspacePluginSettingsService.ts (PR #300585) and the workspace plugin system. This is a missing guard in the code they introduced.

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