MultiBlockMigrationsOngoing

Runtime code replacement is blocked while a multi-block migration is still executing. Wait for the ongoing migrations to complete (check the multi-block migrations cursor) before retrying set_code or the authorized upgrade.

Declared by the System pallet; it classifies to the semantic code too_early.

Remediation

The required window has not opened yet; wait some blocks and retry

The same explanation is available in the terminal: btcli explain MultiBlockMigrationsOngoing.