[ZK Stack] - Failed update from external-node:2.0-v26.7.0-alpha to matterlabs/external-node:v27.2.0-alpha

[SwatGuard]

Team or Project

Syncnode

Module Affected

• System contracts (era-system-contracts)
• Smart contracts (era-contracts)
• zkEVM (era-zk_evm)
• Server (zksync-era)
• Prover (era-boojum)
• Fee withdrawer (era-fee-withdrawer)
• Block Explorer (clock-explorer)
• Portal - Wallet + Bridge (dapp-portal)
• Other (please specify below)

Rust Version

not using

Operating System

• Ubuntu
• MacOS
• Windows
• Other (Please specify below)

Issue Description

We tried to update our node from external-node:2.0-v26.7.0-alpha to matterlabs/external-node:v27.2.0-alpha and got:

external-node-1  | Error: failed fetching remote part of node config from main node
external-node-1  | 
external-node-1  | Caused by:
external-node-1  |     0: Unable to fetch required config values from the main node
external-node-1  |     1: Failed to fetch l2 multicall3
external-node-1  |     2: Request rejected `403```

Rolling back is not possible due to this error:
external-node-1  | error: migration 20250218134333 was previously applied but is missing in the resolved migrations


### Expected Behavior

Should managed to update successfully 

### Current Behavior

Node is down

### Repository Link (if applicable)

_No response_

### Additional Details

_No response_

### Prior Research

- [X] Yes, I searched for similar issues and did not find any matching ones.

[itegulov]

You should run latest non-alpha version of EN which in this case is v27.1.1. v27.2.0 is marked as alpha as it is not ready yet. From what I can see the issue you posted comes from the fact that mainnet node hasn't been upgraded to v27 yet, so that's kind of expected.