LLM API migration errors and fixes on AI Engineer Guidehttps://aiengineerguide.com/tools/model-migration-linter/errors/Recent content in LLM API migration errors and fixes on AI Engineer GuideHugoen-USCopyright © 2024-2026, Nesin Technologies LLP.Mon, 02 Nov 2026 00:00:00 +0530A document block in an assistant message returns a 400 in API version 2026-10-21https://aiengineerguide.com/tools/model-migration-linter/errors/anthropic-api-2026-10-21-document-in-assistant/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/anthropic-api-2026-10-21-document-in-assistant/Assistant message prefill returns a 400 on Claude Haiku 5.5https://aiengineerguide.com/tools/model-migration-linter/errors/claude-haiku-5-5-prefill/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-haiku-5-5-prefill/Assistant message prefill returns a 400 on Claude Sonnet 5.5https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-prefill/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-prefill/Beta headers to remove when moving to Claude Sonnet 5.5https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-legacy-beta-headers/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-legacy-beta-headers/Chat Completions function tools on GPT-6 Luna, GPT-6 Sol and GPT-5.6 need reasoning_effort nonehttps://aiengineerguide.com/tools/model-migration-linter/errors/openai-chat-tools-need-reasoning-effort-none/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/openai-chat-tools-need-reasoning-effort-none/citations on a user text block return a 400 in API version 2026-10-21https://aiengineerguide.com/tools/model-migration-linter/errors/anthropic-api-2026-10-21-citations-in-user-text/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/anthropic-api-2026-10-21-citations-in-user-text/Claude Sonnet 5.5 thinks by default when thinking is omittedhttps://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-thinking-on-by-default/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-thinking-on-by-default/computer_20250124 isn't accepted by Claude Sonnet 5.5 or Haiku 5.5https://aiengineerguide.com/tools/model-migration-linter/errors/claude-5-5-computer-use-version/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-5-5-computer-use-version/fine-grained-tool-streaming-2025-05-14 with a toolset returns a 400https://aiengineerguide.com/tools/model-migration-linter/errors/claude-5-5-fine-grained-tool-streaming-header/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-5-5-fine-grained-tool-streaming-header/Forced tool_choice on Claude Haiku 5.5 skips thinkinghttps://aiengineerguide.com/tools/model-migration-linter/errors/claude-haiku-5-5-forced-tool-choice/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-haiku-5-5-forced-tool-choice/GPT-6.1 Sol doesn't support reasoning effort none or minimalhttps://aiengineerguide.com/tools/model-migration-linter/errors/openai-gpt-6-1-sol-reasoning-effort-none-minimal/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/openai-gpt-6-1-sol-reasoning-effort-none-minimal/max_tokens isn't compatible with OpenAI o-series modelshttps://aiengineerguide.com/tools/model-migration-linter/errors/openai-max-tokens-o-series/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/openai-max-tokens-o-series/prompt_cache_retention becomes prompt_cache_options.ttl on GPT-6https://aiengineerguide.com/tools/model-migration-linter/errors/openai-gpt-6-prompt-cache-retention/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/openai-gpt-6-prompt-cache-retention/reasoning effort none returns a 400 on GPT-6 Astrahttps://aiengineerguide.com/tools/model-migration-linter/errors/openai-gpt-6-astra-reasoning-effort-none/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/openai-gpt-6-astra-reasoning-effort-none/Remove temperature, top_p and logprobs on GPT-6 unless reasoning effort is nonehttps://aiengineerguide.com/tools/model-migration-linter/errors/openai-gpt-6-sampling-with-reasoning/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/openai-gpt-6-sampling-with-reasoning/stop isn't supported on o3 and o4-minihttps://aiengineerguide.com/tools/model-migration-linter/errors/openai-stop-o3-o4-mini/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/openai-stop-o3-o4-mini/temperature, top_p and logprobs raise an error on GPT-5 modelshttps://aiengineerguide.com/tools/model-migration-linter/errors/openai-gpt-5-sampling-parameters/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/openai-gpt-5-sampling-parameters/temperature, top_p and top_k can return an error on Claude Haiku 5.5https://aiengineerguide.com/tools/model-migration-linter/errors/claude-haiku-5-5-sampling-parameters/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-haiku-5-5-sampling-parameters/temperature, top_p and top_k return a 400 in API version 2026-10-21https://aiengineerguide.com/tools/model-migration-linter/errors/anthropic-api-2026-10-21-sampling-parameters/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/anthropic-api-2026-10-21-sampling-parameters/temperature, top_p and top_k return an error on Claude Sonnet 5.5https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-sampling-parameters/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-sampling-parameters/thinking type disabled returns a 400 on Claude Sonnet 5.5https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-thinking-disabled/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-thinking-disabled/thinking type enabled with budget_tokens returns a 400 on Claude Haiku 5.5https://aiengineerguide.com/tools/model-migration-linter/errors/claude-haiku-5-5-thinking-budget/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-haiku-5-5-thinking-budget/thinking type enabled with budget_tokens returns a 400 on Claude Sonnet 5.5https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-thinking-budget/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-thinking-budget/Tool calling on GPT-6 Astra, GPT-6.1 Sol and GPT-6.1 Terra requires the Responses APIhttps://aiengineerguide.com/tools/model-migration-linter/errors/openai-gpt-6-chat-tools-require-responses/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/openai-gpt-6-chat-tools-require-responses/tool_choice any or tool returns a 400 on Claude Sonnet 5.5https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-forced-tool-choice/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-forced-tool-choice/Top-level output_format returns a 400 on Claude Sonnet 5.5https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-output-format/Mon, 02 Nov 2026 00:00:00 +0530https://aiengineerguide.com/tools/model-migration-linter/errors/claude-sonnet-5-5-output-format/