Unity-Technologies/UnityCsReference · error · Exception

Invalid severity '' in line '{line}'

Error message

Invalid severity '' in line '{line}'

What it means

Thrown when a rule line has ':id | signature' but no third field. After consuming id and signature, NextToken returns separatorIndex -1, meaning the severity field is missing, so the parser reports an empty severity.

Source

Thrown at Editor/Mono/Scripting/RestrictedApisValidation/RestrictedApisConfig.cs:161

            }

            currentMembersConfig = assemblySpecificConfigs._restrictedMembersConfig;
            currentTypesConfig = assemblySpecificConfigs._restrictedTypesConfig;
            return;
        }

        if (token[0] != ':')
        {
            // Invalid line
            throw new Exception($"Invalid configuration line: '{line}'");
        }

        flags.Set(PerAssemblyConfigFlag, false); // Reset per-assembly configuration flag

        var id = token.Slice(1);
        var signature = NextToken(ref lineSpan, out separatorIndex);
        if (separatorIndex == -1)
            throw new Exception($"Invalid severity '' in line '{line}'");

        var severitySpan = NextToken(ref lineSpan, out separatorIndex);
        var description = "";
        var documentationUrl = "";
        if (separatorIndex != -1)
        {
            description = NextToken(ref lineSpan,  out separatorIndex).ToString();
            if (separatorIndex != -1)
            {
                documentationUrl = NextToken(ref lineSpan,  out separatorIndex).ToString();
            }
        }

        if (!Int32.TryParse(id, out var intId))
        {
            throw new Exception($"Id must be a number (line: '{line}')");
        }

View on GitHub (pinned to 225b0fbdb5)

Solutions

  1. Add the severity field: ':id | signature | error' (or warning/info).
  2. Double-check the line has at least three '|'-delimited fields: id, signature, severity.

Example fix

// before
:1001 | System.IO.File::Open
// after
:1001 | System.IO.File::Open | error
Defensive patterns

Strategy: validation

Validate before calling

// A rule line needs at least three '|'-delimited fields: :id | signature | severity.
var parts = line.Split('|');
if (parts.Length < 3 && line.AsSpan().Trim().StartsWith(":"))
    throw new FormatException($"Rule missing severity field: '{line}'");

Try / catch

try { config = RestrictedApisConfig.Load(path); }
catch (Exception ex) when (ex.Message.Contains("Invalid severity ''"))
{ /* add the severity field after the signature */ }

Prevention

When it happens

Trigger: A line like ':id | signature' with no severity token after the second '|'.

Common situations: Truncating a rule line, or forgetting the severity field when writing a rule.

Related errors

AI-assisted analysis of Unity-Technologies/UnityCsReference@225b0fbdb5 (2026-08-13). Data as JSON: /api/errors/feeb7f12e4a17b1f. Report an issue: GitHub.