Errors/Chain errors
MaximumContributionTooLow
Check the argument values against the operation schema
The new_max_contribution passed to set_max_contribution is below the crowdloan's min_contribution or below the creator's existing contribution. Check both against the Crowdloans entry and the creator's Contributions entry.
Declared by the Crowdloan pallet; it classifies to the semantic code invalid_argument.
Remediation
Check the argument values against the operation schema
The same explanation is available in the terminal: btcli explain MaximumContributionTooLow.