Missing Tool Result Block After Tool Use This error suggests that after a tool use block in the conversation, you did not include the corresponding tool result block, which is required by the API. To resolve this: 1. Ensure that any `tool_use` block is i

[Belkins]

Bug Description
stuck on Error: API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.156: Did not find 1 tool_result block(s) at the beginning of this message. Messages following tool_use blocks must begin with a matching number of
tool_result blocks."}}

Environment Info

• Platform: macos
• Terminal: Apple_Terminal
• Version: 0.2.14
• Feedback ID: 4441d4b9-707d-4983-b467-74dd96d8ddc5

[myzie]

I ran across this error when using the Anthropic API (not Claude Code) and I assumed it was my fault initially. However I've looked more into it and I'm seeing something that looks like it could be a mistake on Anthropic's side. And I'm wondering if Claude Code may be subject to the same situation occasionally.

The key message sequence seems to be:

• An assistant message with two content blocks in an atypical order (tool_use first, text second)
• Then a user message with the corresponding tool_result

Note the assistant's own text content is BETWEEN the "tool_use" and the "tool_result" in the overall sequence. This seems to be the atypical order, as Claude most often will respond with (text first, tool_use second).

Here's an excerpt from the messages that cause the problem for me:

[
    ... truncated ...
  {
    "role": "user",
    "content": [
      {
        "type": "tool_result",
        "tool_use_id": "toolu_01Ya9WAYPEZjkyjxcw8J2SxB",
        "content": "Error: Failed to read directory /home. open /home: operation not permitted"
      }
    ]
  },
  {
    "role": "assistant",
    "content": [
      {
        "id": "toolu_01FGfUwSu2N7d8f1tAFh4snU",
        "type": "tool_use",
        "name": "ListDirectory",
        "input": {
          "path": "."
        }
      },
      {
        "type": "text",
        "text": "I apologize for the confusion. It seems we don't have permission to access the /home directory directly. Let's try listing the current directory instead:"
      }
    ]
  },
  {
    "role": "user",
    "content": [
      {
        "type": "tool_result",
        "tool_use_id": "toolu_01FGfUwSu2N7d8f1tAFh4snU",
        "content": "Directory listing for ..."
      }
    ]
  }
]

The error I get is this:

`tool_use` ids were found without `tool_result` blocks immediately after: toolu_01FGfUwSu2N7d8f1tAFh4snU.
Each `tool_use` block must have a corresponding `tool_result` block in the next message.

Note that the tool_result toolu_01FGfUwSu2N7d8f1tAFh4snU IS directly after the assistant message.

Curious if this resonates with anyone else that stumbles across this!

[johnewart]

Actually, I ran into this just this evening as well - my solution was to order content blocks in messages like this:

1. Tool Result Block
2. Text Block
3. Tool Request Block

This makes the API happy and guarantees responses are always right after requests, if you take all the blocks out and process them in literal order.

I think this is a bug in the Anthropic API - it used to work fine with the blocks out of order until just recently.

@myzie

[myzie]

Thanks @johnewart for chiming in!

[sharyar]

Running into the same issue as well.
This becomes pretty complicated when it comes to building agents where you may not necessarily have a lot of control with the ordering of messages.

[Kitenite]

I thought i was going crazy but seems like the Anthropic API calls occasionally will return the messages out of order with tool use and result

[TweedBeetle]

Happening to me right now out of nowhere also

[notabene01]

@TweedBeetle same here, right now
version 0.2.100

[IlyaMaksheev]

Hello. Same for me.

[ravishrawal]

hi same for me

[henricook]

From an affected user in Claude Code CLI: Is there a way I can recover my conversation when this happens? There's a lot of context I don't want to lose!

Edit: it's extremely hairy but I managed to rescue this session by finding the session JSON under ~/.claude/projects/_path_to_my_project/[LATEST-SESSION-STORE-HERE].json and editing out messages that caused the error (in my case the last 6 or so lines) before continuing the session with claude -c