LykosAI/StabilityMatrix · error · InvalidOperationException

Expected colon.

Error message

Expected colon.

What it means

Thrown by ParseNetwork when the token after the network type should be a ':' separator scoped as 'punctuation.separator.variable.prompt' but is missing or scoped differently. The parser requires the strict '<type:name...>' structure.

Solutions

1. Add the ':' separator between type and name: '<lora:name:0.8>'
2. Do not put spaces or other characters between the type and ':'
3. Verify the tokenizer scopes the ':' as punctuation.separator.variable.prompt
4. Catch InvalidOperationException and highlight the malformed tag for the user

Example fix

// before
var prompt = "<lora myModel:0.8>";
// after
var prompt = "<lora:myModel:0.8>";

bool HasColonSeparator(string tag) => System.Text.RegularExpressions.Regex.IsMatch(tag, "^<[a-zA-Z]+:");

null

try { var node = builder.Parse(prompt); } catch (InvalidOperationException ex) when (ex.Message.Contains("Expected colon")) { // highlight the tag missing ':' after the type }

When it happens

Trigger: Input like '<lora name:0.8>' (space instead of colon), '<lora-name:0.8>' if '-' tokenizes as something else, or '<lora>' with nothing following the type.

Common situations: Users rewriting LoRA tags by hand and omitting the colon; prompts converted between syntaxes that use spaces or '=' instead of ':'; autocomplete tools inserting the tag name without the separator.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• Expected opening bracket.
• Expected network type.
• Expected network name.
• Expected network weight.
• Expected closing bracket.

AI-assisted analysis of LykosAI/StabilityMatrix@af93d6ef57 (2026-09-12). Data as JSON: /api/errors/7953cd11943d8da4. Report an issue: GitHub.

Appendix: source

Thrown at StabilityMatrix.Core/Models/PromptSyntax/PromptSyntaxBuilder.cs:252

    private NetworkNode ParseNetwork()
    {
        var beginNetworkToken = ConsumeToken();
        if (
            beginNetworkToken is null
            || !beginNetworkToken.Scopes.Contains("punctuation.definition.network.begin.prompt")
        )
            throw new InvalidOperationException("Expected opening bracket.");

        // type
        var typeToken = PeekToken();
        if (typeToken is null || !typeToken.Scopes.Contains("meta.embedded.network.type.prompt"))
            throw new InvalidOperationException("Expected network type.");
        var type = ParseIdentifier();

        // colon
        var colonToken = ConsumeToken();
        if (colonToken is null || !colonToken.Scopes.Contains("punctuation.separator.variable.prompt"))
            throw new InvalidOperationException("Expected colon.");

        // name
        var nameToken = PeekToken();
        if (nameToken is null || !nameToken.Scopes.Contains("meta.embedded.network.model.prompt"))
            throw new InvalidOperationException("Expected network name.");
        var name = ParseText();

        // model weight, clip weight
        NumberNode? modelWeight = null;
        NumberNode? clipWeight = null;

        // colon
        var nextToken = PeekToken();
        if (nextToken is not null && nextToken.Scopes.Contains("punctuation.separator.variable.prompt"))
        {
            ConsumeToken(); // consume colon

            // Parse the model weight.

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