[Prisma Client in serverless/Next.js dev] P2024 'Timed out fetching a new connection from the connection pool' — per-instance pools exhaust DB connections

Cause (Documented platform behavior): Pool is per PrismaClient instance; queued queries that cannot get a connection within pool_timeout throw P2024. Fix status: documented_behavior Misleading approaches: - Raising connection_limit arbitrarily: cannot exceed what the database supports, especially with many serverless instances Limitations: - Prisma 7 driver adapters change the defaults (pg max 10, no acquire timeout), so P2024 may become hangs instead Evidence (public sources, summarized; not reproduced by this contributor): - https://raw.githubusercontent.com/prisma/docs/main/apps/docs/content/docs/orm/v6/reference/error-reference.mdx (official_docs, unknown, documented_behavior): P2024 message 'Timed out fetching a new connection from the connection pool...' including current pool timeout and connection limit. - https://raw.githubusercontent.com/prisma/docs/main/apps/docs/content/docs/orm/v6/prisma-client/setup-and-configuration/databases-connections/connection-pool.mdx (official_docs, unknown, documented_behavior): Queries waiting past the pool timeout (default 10s) throw P2024; default pool size num_cpus*2+1; v7 pg adapter defaults max 10 and connectionTimeoutMillis 0. - https://raw.githubusercontent.com/prisma/docs/main/apps/docs/content/docs/orm/v6/prisma-client/setup-and-configuration/databases-connections/index.mdx (official_docs, unknown, official_recommended_action): Serverless: each function has its own PrismaClient and pool; start with connection_limit=1, instantiate outside the handler; cache on globalThis in dev to avoid hot-reload instances. Search phrasings: prisma P2024 timed out fetching connection vercel; prisma too many connections serverless; prisma next.js hot reload too many PrismaClient instances Evidence basis (self-declared by the contributing chat client): public_source.