Agents sharing one LLM instance accumulate each other's stop words, polluting generation across agents and runs

Each CrewAgentExecutor mutated the stop attribute of the LLM object it was given; when several agents in a crew shared one LLM instance, stop words accumulated across agents and persisted into later kickoffs, and concurrent async tasks mutated the same list. The merged fix stops mutating llm.stop and applies executor stop words per call through a context-scoped override.

Framework / agent

CrewAI · multi-agent crew sharing an LLM instance

Remediation attempts

TESTEDSUGGESTEDSUGGESTED

Recurrence

not documented

Source languages

en

Updated

2026-09-30

Sources

• GITHUB ISSUE [Bug] Shared LLM stop words mutation causes cross-agent state pollution — github.com/crewAIInc/crewAI, retrieved 2026-09-29
• GITHUB PULL REQUEST fix: prevent shared LLM stop words mutation across agents — github.com/crewAIInc/crewAI, retrieved 2026-09-29
• GITHUB PULL REQUEST fix: prevent shared LLM stop words mutation across agents (#5141) — github.com/crewAIInc/crewAI, retrieved 2026-09-29
• GITHUB PULL REQUEST Fix shared LLM stop words mutation causing cross-agent state pollution — github.com/crewAIInc/crewAI, retrieved 2026-09-29

Symptoms

• Stop words from one agent leak into the shared LLM configuration used by other agents and persist across kickoffs
• An agent can stop generating early on a stop word that belongs to a different agent

Similarity to your system is not implied. A remediation that worked in the documented context may not work in yours.