What causes "newValPubKey is not of type crypto.PubKey" in unionlabs/union?

Use the `uniond testnet` CLI path where the generated validator key is inserted as a crypto.PubKey

newValPubKey is not of type crypto.PubKey

Error message

newValPubKey is not of type crypto.PubKey

What it means

getCommandArgs requires appOpts.Get(server.KeyUserPubKey) to be a crypto.PubKey interface value (e.g., an ed25519.PubKey injected by the testnet key generation). A nil value or a non-PubKey type — notably a raw string or []byte from configuration — fails the assertion and panics.

Source

Thrown at uniond/cmd/uniond/cmd/testnet.go:226

			panic(err)
		}
	}

	return app
}

// parse the input flags and returns valArgs
func getCommandArgs(appOpts servertypes.AppOptions) (valArgs, error) {
	args := valArgs{}

	newValAddr, ok := appOpts.Get(server.KeyNewValAddr).(bytes.HexBytes)
	if !ok {
		panic("newValAddr is not of type bytes.HexBytes")
	}
	args.newValAddr = newValAddr
	newValPubKey, ok := appOpts.Get(server.KeyUserPubKey).(crypto.PubKey)
	if !ok {
		panic("newValPubKey is not of type crypto.PubKey")
	}
	args.newValPubKey = newValPubKey
	newOperatorAddress, ok := appOpts.Get(server.KeyNewOpAddr).(string)
	if !ok {
		panic("newOperatorAddress is not of type string")
	}
	args.newOperatorAddress = newOperatorAddress
	upgradeToTrigger, ok := appOpts.Get(server.KeyTriggerTestnetUpgrade).(string)
	if !ok {
		panic("upgradeToTrigger is not of type string")
	}
	args.upgradeToTrigger = upgradeToTrigger

	// validate  and set accounts to fund
	accountsString := cast.ToString(appOpts.Get(flagAccountsToFund))

	for _, account := range strings.Split(accountsString, ",") {
		if account != "" {

View on GitHub (pinned to 031785bb6d)

Solutions

Use the `uniond testnet` CLI path where the generated validator key is inserted as a crypto.PubKey
When setting options yourself, construct the concrete type first (e.g., ed25519.PubKey{Key: bytes}) before viper.Set
Convert any string-encoded pubkey at the boundary — never rely on the assertion to accept it
In forks, return an error naming the missing key instead of panicking

Defensive patterns

Strategy: type-guard

Validate before calling

// The pubkey must be a constructed crypto.PubKey, never a string from config
pubKey := ed25519.PubKey{Key: mustHexDecode(pubKeyHex)}
vpr.Set(server.KeyUserPubKey, pubKey)

Type guard

func optPubKey(appOpts servertypes.AppOptions, key string) (crypto.PubKey, bool) {
	v, ok := appOpts.Get(key).(crypto.PubKey)
	return v, ok
}

Prevention

Convert hex/base64 pubkey strings into crypto.PubKey values at the option boundary
Run testnet through the CLI where key generation inserts the typed value
Assert option presence in test setup before building the app
A nil (missing) option fails the assertion the same way as a wrong type — set defaults explicitly

When it happens

Trigger: Programmatic testnet invocation without the flag wired; supplying the public key as a hex/base64 string in appOpts instead of a constructed crypto.PubKey; flag binding removed by a custom command wrapper.

Common situations: Embedding the testnet runner in tests or tooling; loading options from JSON/viper files where everything deserializes to primitives; refactors that skip server.AddTestnetFlags-style wiring.

Related errors

AI-assisted analysis of unionlabs/union@031785bb6d (2026-08-16). Data as JSON: /api/errors/139203ef5ac5dcc9. Report an issue: GitHub.