deepseek-ai/deepseek-harness · error · LspError

LSP_UNSUPPORTED_OPERATION

LSP_UNSUPPORTED_OPERATION

Error message

server does not support ${request.operation}

What it means

Error "server does not support ${request.operation}" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/lsp/lsp-stdio/src/instance.ts:147

    /* v8 ignore next -- the abortable queue wait rejects a pre-aborted signal before runQuery; this is a belt-and-suspenders guard. */
    if (signal?.aborted) throw abortError(signal)
    // Observe abort during the handshake wait, and never pool a poisoned instance: if the wait ends
    // in failure — an abort on a still-pending handshake, OR `initialize` rejecting (utf-8
    // negotiation, malformed result) without the process exiting — tear the instance down so a
    // permanently-rejecting/pending `ready` can't make every later query for this workspace fail.
    try {
      await abortable(this.ready, signal)
    } catch (error) {
      if (!this.dead) {
        await this.startTeardown()
      }
      throw error
    }
    const capabilities = this.capabilities
    /* v8 ignore next -- `ready` resolves only after capabilities are set, else it rejects above; defensive. */
    if (capabilities === undefined) throw new Error('LSP instance is not initialized')
    if (!supportsOperation(capabilities, request.operation)) {
      throw new LspError(`server does not support ${request.operation}`, 'LSP_UNSUPPORTED_OPERATION')
    }
    if (!supportsTransientOpen(capabilities.textDocumentSync)) {
      throw new LspError('server does not support the transient textDocument/didOpen this host requires', 'LSP_UNSUPPORTED_OPERATION')
    }

    const uri = source.fileUrl
    let opened = false
    try {
      /* v8 ignore next -- guards an abort landing between the ready wait and didOpen; not deterministically reproducible. */
      if (signal?.aborted) throw abortError(signal)
      try {
        await abortable(this.connection.notify('textDocument/didOpen', {
          textDocument: { uri, languageId: request.languageId, version: 1, text: source.text },
        }), signal)
      } catch (error) {
        // A canceled backpressured write or failed stdin leaves the protocol stream unusable before
        // `opened` can arm the didClose cleanup. Teardown here makes the pool evict the instance.
        await this.startTeardown()

View on GitHub (pinned to b150a551b8)

Solutions

1. Choose an operation the server supports, or use a server that implements the operation.

When it happens

Trigger: Thrown at packages/lsp/lsp-stdio/src/instance.ts:147 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of deepseek-ai/deepseek-harness@b150a551b8 (2026-08-24). Data as JSON: /api/errors/a2e12c8df75681eb. Report an issue: GitHub.