libfabric efa_cq_poll_ibv failed to poll cq Transport endpoint is not connected

The EFA provider reported a disconnected endpoint while polling the completion queue. A peer process exit, security-group mismatch, EFA attachment problem, or libfabric transport fault interrupted the fabric path. This entry explains how to confirm the cause, apply the fix, and separate it from adjacent cloud failures.

The literal signature is "libfabric efa_cq_poll_ibv failed to poll cq Transport endpoint is not connected". It is a infrastructure failure associated with cloud RDMA fabrics and multi-node GPU clusters. The line identifies the failing operation or subsystem, while the surrounding evidence decides whether it is the initiating fault or a downstream symptom.

The EFA provider reported a disconnected endpoint while polling the completion queue. A peer process exit, security-group mismatch, EFA attachment problem, or libfabric transport fault interrupted the fabric path. The failure becomes visible at this call site because the operation first requires the missing resource, valid state, healthy peer, or correct result. Earlier log lines and a known-good control carry more causal value than the final wrapper exception.

• The workload stops or loses forward progress after emitting "libfabric efa_cq_poll_ibv failed to poll cq Transport endpoint is not connected".
• A retry on the same configuration reproduces the failure because the causal state has not changed.
• The outer framework exception can hide the rank, node, allocation, or dependency that failed first.
• Increasing timeouts or reducing workload size can suppress the symptom without correcting the cause.

• cloud RDMA fabrics and multi-node GPU clusters
• production-shaped multi-accelerator workloads
• containerized and bare-metal deployments of the same stack

Apply the following checklist to a small reproduction: each box below is a positive signal that you are looking at this exact failure rather than a sibling in the same taxonomy.

• ✓Find the first occurrence of "libfabric efa_cq_poll_ibv failed to poll cq Transport endpoint is not connected" and preserve at least 100 lines before it.
• ✓Identify which rank, node, device, or process emitted the first related warning.
• ✓run fi_info -p efa and an EFA-enabled nccl-tests or OSU control across the same instances. Verify the security group permits all traffic between participating nodes.
• ✓Repeat the same input after the targeted change and require the signature to disappear.
• ✓Resume from latest checkpoint after the EFA fabric control passes only after the control passes.

libfabric efa_cq_poll_ibv failed to poll cq Transport endpoint is not connected

Timestamps and exact values vary across runs, but the pattern. An info-level start, an early WARN, an ERROR carrying the symptom. Is the actual fingerprint you should alert on. The Denpex platform flags this combination automatically.

inspect every peer rank for an earlier exit and confirm the EFA device is present on each instance. The rank that reports the CQ error may only be observing a remote failure. This changes the condition in the causal diagnosis instead of hiding the outer exception. The repeated control proves ownership before recovery from latest checkpoint after the EFA fabric control passes.

# Preserve evidence before restarting
rg -n -i 'error|exception|timeout|failed' <log-file>
nvidia-smi
python -m torch.utils.collect_env

# Find the exact signature in the complete log
rg -n -F -- "libfabric efa_cq_poll_ibv failed to poll cq Transport endpoint is not connected" <log-file>

Adapt the snippet to your framework. The same pattern holds for PyTorch Lightning, Hugging Face Trainer, DeepSpeed, Megatron-LM, and vLLM training wrappers. Where the wrapper exposes a config flag (for examplelr_scheduler_type in Trainer), prefer the flag over the imperative API to keep the schedule declarative and reproducible.

Select the traceback or open the failed terminal, then run Denpex locally to see the initiating rank, collateral failures, exact fix, and verification command without uploading the log.

• The EFA provider reported a disconnected endpoint while polling the completion queue. A peer process exit, security-group mismatch, EFA attachment problem, or libfabric transport fault interrupted the fabric path.
• The decisive evidence is the first log line that precedes "libfabric efa_cq_poll_ibv failed to poll cq Transport endpoint is not connected" and differs from a healthy run.
• A nearby failure remains a competing hypothesis until a control separates configuration, capacity, transport, and hardware causes.