kestra-io/kestra · error · PebbleException

Unknown indent type '%s'.

Error message

Unknown indent type '%s'.

What it means

Thrown by AbstractIndent.abstractApply when the indentType parameter is neither the string 'indent' nor 'nindent'. This is an internal programming error: AbstractIndent is subclassed by IndentFilter (passing 'indent') and NindentFilter (passing 'nindent'), so a user should never see it unless a new subclass is added with a mismatched type string.

Source

Thrown at core/src/main/java/io/kestra/core/runners/pebble/AbstractIndent.java:69

            throw new PebbleException(null, String.format("The '%s' filter expects an integer as argument 'amount'.", indentType), lineNumber, self.getName());
        }

        int amount = ((Long) args.get("amount")).intValue();
        if (!(amount >= 0)) {
            throw new PebbleException(null, String.format("The '%s' filter expects a positive integer >=0 as argument 'amount'.", indentType), lineNumber, self.getName());
        }

        String prefix = prefix(args);
        String newLine = getLineSeparator(input.toString());

        if (indentType.equals("indent"))
            // indent filter adds N amount of spaces to each line except for the first one (assuming the first line is already indented in place)
            return input.toString().replace(newLine, newLine + prefix.repeat(amount));
        else if (indentType.equals("nindent")) {
            // nindent filter adds a newline to the string and indents each line by defined amount of spaces
            return (newLine + input).replace(newLine, newLine + prefix.repeat(amount));
        }
        throw new PebbleException(null, String.format("Unknown indent type '%s'.", indentType), lineNumber, self.getName());

    }
}

View on GitHub (pinned to 823fada927)

Solutions

1. If subclassing AbstractIndent, ensure the indentType string passed to abstractApply is exactly 'indent' or 'nindent', or extend the if/else-if chain to handle the new type.
2. Verify the filter subclass constructor passes the correct constant to the parent.
3. Do not attempt to trigger this via templates; fix the Java subclass code.

Example fix

// before — new subclass with unhandled type
public class MyIndentFilter extends AbstractIndent {
    public Object apply(...) {
        return abstractApply(input, args, self, context, lineNumber, "tabs");
    }
}

// after — extend the chain or use an existing type
    return abstractApply(input, args, self, context, lineNumber, "indent");

// In Java, if subclassing AbstractIndent, validate the indentType before calling abstractApply
static String validateIndentType(String indentType) {
    return switch (indentType) {
        case "indent", "nindent" -> indentType;
        default -> throw new IllegalArgumentException(
            "indentType must be 'indent' or 'nindent', got: " + indentType);
    };
}

When it happens

Trigger: A developer extends AbstractIndent and passes an indentType value that is not 'indent' or 'nindent' to abstractApply. This is not reachable through normal Pebble template usage — the type is hardcoded in each filter subclass.

Common situations: Contributing a new indentation-related filter to Kestra's Pebble extension set and forgetting to handle the new indentType branch in the if/else-if chain. Refactoring the two existing filters and introducing a typo in the type constant.

Related errors

• The '%s' filter expects an integer as argument 'amount'.
• The '%s' filter expects a positive integer >=0 as argument '
• Too many rendering attempts
• Cannot concat {} with {}
• Could not perform greater than or equals comparison

AI-assisted analysis of kestra-io/kestra@823fada927 (2026-08-14). Data as JSON: /api/errors/9199453a2e72b63a. Report an issue: GitHub.