Enhance validator reliability with fallback beacon nodes

Prysm's validator client supports multiple beacon node endpoints for redundancy and load balancing. If the active endpoint becomes unresponsive or unsynced, the validator automatically fails over to the next endpoint in the list.

Prerequisites

• Prysm installed (via official release binaries or built from source).
• At least two beacon nodes running and accessible from the machine running the validator client.
• Validator keys and a wallet already created (e.g., via prysm validator wallet create).

Connecting with gRPC (default)

Use --beacon-rpc-provider on the validator client with a comma-separated list of host:port pairs. The gRPC port defaults to 4000.

./prysm.sh validator \
  --wallet-dir=/path/to/wallet \
  --beacon-rpc-provider=localhost:4000,remote-beacon.example.com:4000,another-beacon:4000 \
  --datadir=/path/to/validator/data \
  --mainnet \
  --suggested-fee-recipient=0xYourEthereumAddressForFees

gRPC deprecation

gRPC will remain the default and fully supported through v8 (expected in 2026) but will eventually be removed in favor of the REST API.

Connecting with REST

Use --beacon-rest-api-provider on the validator client with a comma-separated list of HTTP URLs. Also pass --enable-beacon-rest-api on the validator client to switch it from gRPC to REST when communicating with the beacon node. The beacon node's REST API is served on port 3500 by default (controlled on the beacon node side by --http-port, alias --grpc-gateway-port).

./prysm.sh validator \
  --wallet-dir=/path/to/wallet \
  --beacon-rest-api-provider=http://localhost:3500,http://remote-beacon.example.com:3500,http://another-beacon:3500 \
  --enable-beacon-rest-api \
  --datadir=/path/to/validator/data \
  --mainnet \
  --suggested-fee-recipient=0xYourEthereumAddressForFees

REST is experimental

The REST API path (--enable-beacon-rest-api) is experimental and not recommended for Mainnet. Use gRPC for production validators.

All flags in both examples go on the validator client binary. The beacon node does not require any additional flags to serve its HTTP API — it is enabled by default on port 3500.

Fallback behavior

Both gRPC and REST use sync-status-aware failover logic:

• The validator checks that each candidate endpoint is reachable and fully synced before using it.
• If the active endpoint becomes unhealthy or unsynced, the validator tries each remaining endpoint in order and stops at the first healthy one.

Health checks and --max-health-checks

The --max-health-checks flag (on the validator client) controls how many consecutive failed health checks are tolerated before the validator shuts down gracefully.

Value	Behavior
0 (default)	Indefinite — the validator never times out due to health check failures and keeps retrying forever.
Positive integer (e.g., 10)	The validator shuts down after that many consecutive failed checks, allowing a process manager to restart it.

Example with a finite limit:

./prysm.sh validator \
  --wallet-dir=/path/to/wallet \
  --beacon-rpc-provider=localhost:4000,remote-beacon.example.com:4000 \
  --max-health-checks=10 \
  --datadir=/path/to/validator/data \
  --mainnet

While health checks are failing, the validator logs:

Failed health check, beacon node is unresponsive  fails=X maxFails=Y url=...

When the limit is reached:

Maximum health checks reached. Stopping health check routine  maxFails=Y url=...

Monitoring and testing

• Monitor logs for Failed health check and Health status changed messages.
• Use Prometheus and Grafana (enabled via --monitoring-port=8081) to track validator performance.
• Test fallbacks by shutting down one beacon node and confirming the validator continues attesting and proposing via the remaining endpoints.

Other common flags

• --graffiti="YourCustomGraffiti": Optional custom block graffiti.
• --wallet-password-file=/path/to/password.txt: For non-interactive runs.
• --enable-doppelganger: Enables doppelganger protection. If the primary node is down at startup, this may delay the validator — test in a dev environment before enabling on Mainnet.
• --tls-cert / --tls-key: For encrypted gRPC connections.
• --mainnet, --holesky, or --sepolia: Network selection flag.

If you encounter issues, join the Prysm Discord community for support.