OpenRouter error
OpenRouter 400 string_too_long: what it means and how to fix it
400 string_too_longRetry? Not statedLast verified 1 documented fix1 source
What it means
A single string field in the request (system prompt, user message, etc.) exceeded the provider's per-field character limit.
Causes
- One string field longer than the provider allows
How to fix it
- Fix 1.
Shorten the offending field to the provider's per-field character limit.
More OpenRouter errors
All 32 OpenRouter errors400 invalid_requestRetry? Not stated400 invalid_promptRetry? Not stated400 context_length_exceededRetry? Not stated400 max_tokens_exceededRetry? Not stated400 token_limit_exceededRetry? Not stated400 invalid_imageRetry? Not stated400 image_too_largeRetry? Not stated400 image_too_smallRetry? Not stated
HTTP 400 at other providers
Compare 400 across providers400 ValidationExceptionRetry? NoAmazon Bedrock400 ServiceQuotaExceededExceptionRetry? YesAmazon Bedrock400 IncompleteSignatureRetry? Not statedAmazon Bedrock400 InvalidActionRetry? Not statedAmazon Bedrock400 NotAuthorizedRetry? Not statedAmazon Bedrock400 RequestExpiredRetry? Not statedAmazon Bedrock400 invalid_request_errorRetry? Not statedAnthropic API400 invalid_request_error (spend limit reached)Retry? Not statedAnthropic API400 Bad RequestRetry? Not statedAzure OpenAI400 content_filterRetry? Not statedAzure OpenAI400 Bad RequestRetry? Not statedCohere API400 Bad Request (too many tokens)Retry? Not statedCohere API
FAQ
What does the OpenRouter error "400 string_too_long" mean?
A single string field in the request (system prompt, user message, etc.) exceeded the provider's per-field character limit.
How do I fix OpenRouter "400 string_too_long"?
Shorten the offending field to the provider's per-field character limit.
Should I retry OpenRouter "400 string_too_long"?
Not stated. The official docs do not say whether this error is retryable.
Which other AI APIs return HTTP 400?
Per their official error docs: Amazon Bedrock (400 ValidationException; 400 ServiceQuotaExceededException; 400 IncompleteSignature; 400 InvalidAction; 400 NotAuthorized; 400 RequestExpired), Anthropic API (400 invalid_request_error; 400 invalid_request_error (spend limit reached)), Azure OpenAI (400 Bad Request; 400 content_filter), Cohere API (400 Bad Request; 400 Bad Request (too many tokens)), DeepSeek API (400 - Invalid Format), Gemini API (400 invalid_request; 400 failed_precondition; 400 parameter_unknown; 400 INVALID_ARGUMENT; 400 FAILED_PRECONDITION), Groq API (400 Bad Request), Mistral API (400 Bad request), OpenAI API (400 invalid_request_error (Invalid service_tier argument); 400 BadRequestError), Vertex AI (400 INVALID_ARGUMENT / FAILED_PRECONDITION), xAI API (400 Bad Request).
Sources
Last verified against 1 source: OpenRouter's official docs and official SDK repositories.
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