Errors/Chain errors
TooBig
A chain-side capacity limit was hit; reduce the size or count of the request
The preimage exceeds the maximum size the pallet will store on-chain (4 MiB). Check the byte length of the preimage against the pallet's MAX_SIZE limit before noting it.
Declared by the Preimage pallet; it classifies to the semantic code limit_exceeded.
Remediation
A chain-side capacity limit was hit; reduce the size or count of the request
The same explanation is available in the terminal: btcli explain TooBig.