microsoft/aspire · error · ArgumentException

Connector Namespace resource names can contain only ASCII…

Error message

Connector Namespace resource names can contain only ASCII letters, numbers, hyphens, and underscores.

What it means

Connector Namespace resource names must use only ASCII letters, digits, hyphens, and underscores; Azure rejects any other character. ValidateConnectorResourceName throws ArgumentException naming the offending parameter when any character falls outside this set.

Solutions

Remove or replace disallowed characters (e.g. '.' -> '-')
Use a sanitizer that maps the name to [A-Za-z0-9_-] only
Avoid deriving names directly from paths, URLs, or user input

Example fix

// before
.AddConnection("my app.conn", ...)
// after
.AddConnection("my-app-conn", ...)

Defensive patterns

Strategy: validation

Validate before calling

if (name.Any(c => !char.IsAsciiLetterOrDigit(c) && c is not '-' and not '_'))
    throw new ArgumentException("Name must contain only ASCII letters, digits, '-', '_'.", nameof(name));

Try / catch

try { builder.AddConnection(name, ...); }
catch (ArgumentException ex) { log.LogError(ex, "Name contains invalid characters"); }

Prevention

Sanitize names derived from paths/URLs/user input
Use a canonical slug function for all resource names
Avoid non-ASCII identifiers in infrastructure code

When it happens

Trigger: Passing a name containing spaces, dots, slashes, or non-ASCII/Unicode characters to AddConnection, WithAccessPolicy, WithIdentityAccessPolicy, or AddMcpServerConfig.

Common situations: Deriving names from project paths or URLs (dots/slashes), using localized or emoji characters, copying names with trailing spaces or casing artifacts.

Understand the failure class

Background: "invalid id" errors: invalid identifier format — why libraries reject IDs before lookup, and how to fix them — this error's family across 37 libraries.

Related errors

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/c8544d42081cc166. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting.Azure.ConnectorNamespace/AzureConnectorNamespaceExtensions.cs:765

        }
    }

    private static void ValidateConnectorResourceName(string name, string paramName)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(name, paramName);
        if (name.Length is < 2 or > 64)
        {
            throw new ArgumentOutOfRangeException(
                paramName,
                name,
                "Connector Namespace resource names must contain between 2 and 64 characters.");
        }

        if (name.Any(static character =>
            !char.IsAsciiLetterOrDigit(character) &&
            character is not '-' and not '_'))
        {
            throw new ArgumentException(
                "Connector Namespace resource names can contain only ASCII letters, numbers, hyphens, and underscores.",
                paramName);
        }
    }

}

View on GitHub (pinned to 25830f84bd)