Why does SCL validation fail?

SCL validation fails when the declaration does not conform exactly to the SCL:V1 grammar. Common causes include incorrect headers, malformed handles blocks, trailing bytes, or forbidden characters like CR or TAB. Validation halts at the first error and reports the byte offset.

How do I debug SCL validation errors?

Use the SCL validator to get the exact byte offset of the first error. Check the header, handles block syntax, scl block syntax, and encoding. Use a hex editor for byte-level inspection if the error is not visible in a text editor.

SCL Validation Troubleshooting

This page explains how to troubleshoot validation failures in practice. For formal error code definitions and protocol-level error meanings, see SCL error codes. For protocol rules, see the SCL:V1 specification.

SCL is the deterministic, cryptographic identity protocol for AI run declarations. Validation enforces deterministic identity by rejecting invalid declarations before canonical JSON and SHA-256 identity are derived.

How Validation Works

SCL validation is deterministic. It halts at the first error, reports the byte offset, and produces no output. There is no partial validation, no recovery, and no multi-error reporting.

If validation succeeds, the declaration produces canonical JSON and SHA-256 identity. If validation fails, nothing is produced.

Common Validation Errors

Missing or Incorrect Header

The declaration must begin with the exact bytes SCL:V1 at byte offset 0, followed by exactly one blank line. Common mistakes include lowercase scl:v1, missing the blank line separator, or adding whitespace before the header.

Malformed Handles Block

The handles block must begin with handles { on its own line. Each handle definition must be on its own physical line inside the block. Common mistakes include missing the opening brace, placing multiple handles on one line, or omitting required tags.

Invalid SCL Block

The scl block must begin with scl { on its own line. Content must be in valid quoted or raw mode. Common mistakes include missing the opening brace, unclosed quotes, or trailing content after the closing brace.

Trailing Bytes

No content is permitted after the closing brace of the scl block. Any trailing whitespace, newlines, or characters cause validation failure.

Encoding Issues

SCL operates at the byte level. CR characters and TAB characters are forbidden at any position. UTF-8 encoding is enforced strictly. Platform-specific line endings (CRLF) cause validation failure.

Resolving Validation Failures

When validation fails, check these in order:

Verify the header is exactly SCL:V1 at byte 0
Verify exactly one blank line after the header
Verify handles { block syntax and one handle per line
Verify scl { block syntax and content mode
Verify no trailing bytes after the final closing brace
Verify no CR or TAB bytes anywhere in the declaration
Use a hex editor to inspect byte-level content if errors persist

Using the Validator for Debugging

The reference engine reports the exact byte offset of the first error. Use this offset to locate the problem in the declaration.

Run parse first to validate structure. If parse succeeds, run canon and hash to verify identity. If parse fails, fix the reported error before proceeding.

See the Golden Documents for known-valid test inputs and expected outputs.