[BUG] Price feeder fails to query staking module on v5.1.0 due to gRPC service incompatibility

[OneNov0209]

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After upgrading a KiiChain node to v5.1.0, the oracle price-feeder fails to operate correctly.

The price-feeder repeatedly errors when attempting to query staking validator information via gRPC, resulting in failed oracle ticks on every block.
This prevents the price-feeder from submitting price votes and breaks oracle functionality entirely.

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🧪 Environment

• KiiChain node version: v5.1.0

• Price feeder version: v1.3.3

• Network: Mainnet

• gRPC: Enabled (default configuration)

• Setup: Clean installation (no custom patches)

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🔁 Steps to Reproduce

1. Run a KiiChain node upgraded to v5.1.0

2. Ensure the node is fully synced

3. Clone and build price-feeder v1.3.3 without modifications

4. Configure the price-feeder to connect to the node using gRPC

5. Start the price-feeder service:

systemctl start price-feeder

6. Observe the logs

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❌ Observed Behavior

The price-feeder fails on every oracle tick with the following error:

failed to get staking validator: rpc error:
code = Unimplemented desc = unknown service cosmos.staking.v1beta1.Query

Example logs:

INF Received new Chain Height: 25764017 module=oracle_client
WRN Oracle tick failed for height 25764017, err:
failed to get staking validator:
rpc error: code = Unimplemented desc = unknown service cosmos.staking.v1beta1.Query

This error repeats continuously on every new block height.

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✅ Expected Behavior

The price-feeder should be able to:

• Query staking validator information

• Fetch prices from providers

• Submit oracle votes successfully on each block

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🚨 Impact

• Oracle price-feeder is completely non-functional

• No price votes are submitted

• Prices may become stale or unavailable

• Affects all operators running price-feeder on v5.1.0

This represents a High severity issue, as it breaks a core oracle component of the network.

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🔍 Analysis / Suspected Cause

Based on investigation:

• gRPC incompatibility between price-feeder v1.3.3 and node v5.1.0

• The staking gRPC service
cosmos.staking.v1beta1.Query
appears unavailable or incompatible

• gRPC reflection may be disabled or unsupported for this query

• Price-feeder strictly requires gRPC and has no REST fallback

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🛠 Temporary Workaround (Operator Side)

A local workaround was tested by:

• Removing mandatory gRPC validation

• Bypassing staking gRPC calls

• Adding a REST API fallback for validator data

With this workaround:

✅ Price-feeder runs without errors

✅ Prices are fetched correctly

✅ Oracle votes are submitted successfully

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💡 Suggestions

Make gRPC optional in the price-feeder

Add a proper REST API fallback for staking queries

Improve version compatibility checks between node and price-feeder

Document gRPC requirements explicitly for oracle operators

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📝 Additional Notes

Issue is reproducible on a clean setup

No special configuration required to trigger the error

Occurs immediately after starting the price-feeder

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