JuliusBrussee/caveman · error

content must be string or null

Error message

content must be string or null

What it means

Error "content must be string or null" thrown in JuliusBrussee/caveman.

Source

Thrown at cacheengine/cachebench/corpus.go:369

	}
	if !validBoundedText(message.ToolCallID, 2048, true) || !validBoundedText(message.Name, 512, true) {
		return errors.New("invalid message identity")
	}
	if len(message.Content) == 0 && len(message.ToolCalls) == 0 {
		return errors.New("content or tool_calls required")
	}
	if len(message.Content) > limits.MaxMessageBytes || (len(message.Content) > 0 && !json.Valid(message.Content)) {
		return errors.New("content invalid or exceeds limit")
	}
	messageBytes := len(message.Content) + len(message.Role) + len(message.ToolCallID) + len(message.Name)
	if len(message.Content) > 0 {
		var content any
		if err := json.Unmarshal(message.Content, &content); err != nil {
			return errors.New("content must decode")
		}
		if content != nil {
			if _, ok := content.(string); !ok {
				return errors.New("content must be string or null")
			}
		}
	}
	for _, call := range message.ToolCalls {
		if call.Type != "function" || !validBoundedText(call.ID, 2048, false) || !validBoundedText(call.Function.Name, 512, false) || !validUniqueJSONObject([]byte(call.Function.Arguments)) {
			return errors.New("tool call requires function type, id, function name, and JSON arguments")
		}
		messageBytes += len(call.ID) + len(call.Type) + len(call.Function.Name) + len(call.Function.Arguments)
	}
	if messageBytes > limits.MaxMessageBytes {
		return errors.New("message exceeds byte limit")
	}
	if message.Role == "tool" && message.ToolCallID == "" {
		return errors.New("tool message requires tool_call_id")
	}
	return nil
}

View on GitHub (pinned to 27d5a3981a)

Solutions

1. Message content must be a string or null.

When it happens

Trigger: Thrown at cacheengine/cachebench/corpus.go:369 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of JuliusBrussee/caveman@27d5a3981a (2026-08-15). Data as JSON: /api/errors/13ef6a8386a37817. Report an issue: GitHub.