jstedfast/MailKit · error · ArgumentException

Annotation entry paths must not end with '.'.

Error message

Annotation entry paths must not end with '.'.

What it means

AnnotationEntry.ValidatePath also rejects entry-name paths that end with a '.' character. A trailing dot would create an ambiguous or malformed annotation entry when combined with the .priv/.shared scope suffix. Thrown as ArgumentException naming the path parameter.

Solutions

1. Remove the trailing '.' from the path string before passing it
2. Trim trailing dots: path = path.TrimEnd('.')
3. Validate the annotation entry name syntax before constructing

Example fix

// before
var entry = new AnnotationEntry ("comment.", AnnotationScope.Private);
// after
var entry = new AnnotationEntry ("comment.TrimEnd ('.'), AnnotationScope.Private);

if (string.IsNullOrEmpty (path))
    throw new ArgumentException ("Path is required.");
if (path.EndsWith ("."))
    throw new ArgumentException ($"Path '{path}' must not end with '.'.");

bool IsValidPath (string? path) =>
    !string.IsNullOrEmpty (path) && !path.EndsWith ("/") && !path.EndsWith (".");

try {
    var entry = new AnnotationEntry (path, scope);
} catch (ArgumentException ex) when (ex.ParamName == "path") {
    logger.LogError (ex, "Invalid annotation path: {Path}", path);
}

When it happens

Trigger: Calling an AnnotationEntry constructor/factory with a path like "comment." or "/vendor/cmu." — i.e. path[path.Length-1] == '.'.

Common situations: Trailing punctuation introduced by copy-paste, template strings, or splitting entry strings on '.' and reassembling them incorrectly; config files where the value retains a trailing period.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Annotation entry paths must not end with '/'.
• Invalid part-specifier.
• Value cannot be null. (Parameter 'entry')
• Value cannot be null. (Parameter 'partSpecifier')
• Value cannot be null. (Parameter 'part')

AI-assisted analysis of jstedfast/MailKit@9d3859a785 (2026-09-15). Data as JSON: /api/errors/2210d1827ff128d0. Report an issue: GitHub.

Appendix: source

Thrown at MailKit/AnnotationEntry.cs:152

				if (c > 127)
					throw new ArgumentException ($"Invalid character in annotation entry path: '{c}'.", nameof (path));

				if (c >= '0' && c <= '9' && pc == '/')
					throw new ArgumentException ("Invalid annotation entry path.", nameof (path));

				if ((pc == '/' || pc == '.') && (c == '/' || c == '.'))
					throw new ArgumentException ("Invalid annotation entry path.", nameof (path));

				pc = c;
			}

			int endIndex = path.Length - 1;

			if (path[endIndex] == '/')
				throw new ArgumentException ("Annotation entry paths must not end with '/'.", nameof (path));

			if (path[endIndex] == '.')
				throw new ArgumentException ("Annotation entry paths must not end with '.'.", nameof (path));
		}

		static void ValidatePartSpecifier (string partSpecifier)
		{
			if (partSpecifier == null)
				throw new ArgumentNullException (nameof (partSpecifier));

			char pc = '\0';

			for (int i = 0; i < partSpecifier.Length; i++) {
				char c = partSpecifier[i];

				if (!((c >= '0' && c <= '9') || c == '.') || (c == '.' && (pc == '.' || pc == '\0')))
					throw new ArgumentException ("Invalid part-specifier.", nameof (partSpecifier));

				pc = c;
			}

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