A sourced fix-playbook workspace for AI and agent engineers. Find the root cause, the affected version, the rollback-safe next step, and edge-case audits.
RunnableParallel's async execution paths (ainvoke and _atransform) do not read the `max_concurrency` configuration key, causing all branches to run concurrently and potentially violating downstream rate limits. The sync path correctly uses a thread pool with the configured limit.
The OpenAI and ChatOpenAI classes in langchain-openai default to gpt-3.5-turbo-instruct and gpt-3.5-turbo respectively. OpenAI shut down gpt-3.5-turbo-instruct on September 28, 2026, and gpt-3.5-turbo will be shut down on October 23, 2026. Users who do not explicitly pass a model will encounter API errors. The recommended replacement gpt-5.6-terra is a reasoning model and does not support the legacy completions endpoint, requiring a strategic change to defaults.
Next.js dev server leaks memory when a route handler executes an infinite async loop, eventually crashing the process. Production build and plain Node.js do not exhibit this issue.
Calling stream() or astream() on ChatPerplexity with a stop argument raises TypeError because the streaming implementation incorrectly sends stop_sequences (an Anthropic parameter) to Perplexity's Chat Completions API, which only accepts stop. The bug breaks streaming for any user passing stop sequences.
When a modal is opened via interception over a page that is itself interceptable, performing a router.refresh() or revalidatePath causes the background route refresh request to incorrectly include the Next-Url header, leading to an intercepted response and an MPA fallback, resulting in a full page load and loss of client state.
The Tee context manager in langchain-core does not close the underlying source generator if one or more child iterators are never started, causing resource leaks.
When using MapLibre GL v6 with Next.js Turbopack, the generated worker file contains an import for 'maplibre-gl-shared-dev.mjs', but the emitted file has a hash suffix, causing the worker to fail with 'Worker failed to load'.
ShellToolMiddleware.aafter_agent synchronously executes shutdown commands on the event loop, starving unrelated async tasks; delegate to run_in_executor like abefore_agent.
When prefetching the index page of an optional catch-all dynamic route, the client caches the __PAGE__ entry under a fallback slug. Subsequent navigation to a sibling dynamic path reuses this cached entry without issuing a new request, causing the wrong page content to be displayed.
The hosted Supabase transaction pooler (port 6543) reproduces dropped pipelined PostgreSQL replies when a postgres.js client with prepare:false and max_pipeline:1 sends concurrent unprepared queries. One ParseComplete/ParameterDescription reply is lost and the client promise never resolves, matching Supavisor issues #1061 and fixes #1079/#1176. The deployed pooler version may not include those fixes.
In Next.js production builds (App Router), router.refresh() fails to trigger a server round-trip when the current page was streamed and the URL contains a query string. This causes stale UI after mutations on filtered list pages, with no fetch initiated. The issue is present across multiple versions, with 16.2.12 only affected for query-string URLs, and 16.3.5+ affected for all streamed pages. A fix requires forcing cache invalidation for the current URL during refresh.
Next.js dev server (Turbopack) fails to match routes that are children of a dynamic segment nested inside route groups, returning instant 404 for the entire session. The issue is probabilistic, occurs under module graph load, and is repaired by any file event under app/. Production builds are unaffected.
InMemoryRecordManager treats an explicitly provided empty list for group_ids as if it were None because of truthiness checks. This causes update() to skip length validation and store records with group_id=None, and list_keys() to return all keys instead of an empty result when group_ids=[] is passed. The async methods have the same issue.
The on_tool_error callback does not receive the arbitrary keyword arguments (e.g., tenant, trace_id) that were passed to tool.invoke, while on_tool_start and on_tool_end do. This inconsistency causes loss of critical context during error handling.
In langchain's retry middleware, `should_retry_exception` checks `callable(retry_on)` before `isinstance`, treating exception classes as callables. Passing a single exception class (e.g. `TimeoutError`) invokes the class with the exception, returning a truthy exception instance, causing every exception to be retried regardless of the intended filter.
The helper function _get_data_content_block_types() reconstructs its result from get_args and get_type_hints on every call, even though the result is immutable at runtime. This is called repeatedly by is_data_content_block, leading to ~23ms CPU per ChatOpenAI payload for a 204-message history, blocking the event loop in async applications.
In Next.js 16.3.6 on Vercel, background cache regeneration started during streaming is not tracked by waitUntil, causing it to be aborted when the serverless function exits, resulting in failed revalidations.
langchain-core 1.6.6 contains two type contract inconsistencies: import_attr accepts package=None but raises TypeError due to always using relative imports, and AIMessage/AIMessageChunk.content_blocks return list[str] when content is a list of strings, violating the declared return type list[ContentBlock].
Next.js middleware can return a response with a relative Location header (as allowed by HTTP spec), but the internal adapter passes this value directly to the NextURL constructor, which requires an absolute URL, causing an 'Invalid URL' error.
The bare URL pattern in detect_url incorrectly matches patterns like 'Node.js/Express', '1.5/2.0', and 'python3.12/site-packages', leading to redaction or blocking of non-URL content.
In Next.js 16, lowering watchpack's aggregateTimeout from 200ms to 5ms causes the dev server's initial page scan to fire aggregation callbacks before the scan completes. The first partial aggregation builds the dynamic route table from an incomplete page list, so dynamic pages-router routes return 404 until a later aggregation rebuilds it.
Starting with 16.3.8, the Next.js image optimization server fetches remote images using ImageHttpAgent/ImageHttpsAgent without proxyEnv, causing direct connections that ignore HTTP_PROXY/HTTPS_PROXY and global undici dispatchers. In proxied environments, all remote image requests time out with 504.
Supabase Studio's Exposed functions view computes role access from explicit ACL entries and joins pg_roles, ignoring PostgreSQL's PUBLIC pseudo-role (grantee OID 0). Functions with default PUBLIC EXECUTE are reported as revoked for anon/auth/service_role even though PostgREST allows execution.
When a client component inside a Suspense boundary uses synchronous IO (e.g., Math.random or Date.now) during server rendering, the resumed segment omits the host elements rendered before the sync IO call. This causes a hydration mismatch (React error #418) and the boundary's fallback is replaced with an incomplete subtree.
When a server component calls notFound() inside a dynamic route, the SSR response contains an empty HTML shell with <html id="__next_error__"> instead of rendering the root layout and not-found.tsx content. This occurs because the not-found error is thrown during server rendering and caught by the outer app-render catch, which generates a minimal error document rather than re-rendering the tree with the not-found boundary active.
When a module using next/dynamic is imported by both Pages Router and App Router, ReactLoadablePlugin writes the App Router webpack module id into react-loadable-manifest.json, causing Pages Router client bundle to request the wrong dynamic chunk id and fail hydration with React error #418.
Client-side navigation to ISR pages can serve stale RSC payloads from browser cache without contacting the server, leading to mixed module versions and runtime errors after redeployment.
User reports that all saved SQL queries disappeared from Supabase Studio after a Supabase service incident and page refresh, but database functions remain. This suggests queries were stored in a non-persistent or less redundant location compared to functions.
When multiple SWC plugins are configured and Turbopack's persistent file system cache is enabled (default since Next.js 16.3.0), a restored cache can pair plugin modules with the wrong configuration objects, causing SWC plugin panics and build/dev failures.
File-system-cache `set()` omits the `.rsc` file for PPR routes, causing `get()` to treat the entry as missing after restart or eviction. This results in fallback shell re-rendering and stale RSC payloads for client navigation, leading to data inconsistency.
LangChain, LlamaIndex, and Pydantic
Pinecone, Chroma, Weaviate, Qdrant, and neighboring stores
Next.js, Supabase, and the surrounding app stack