peass-ng/PEASS-ng · error · System.ArgumentOutOfRangeException

Attachments array cannot contain more than 8 items.

Error message

Attachments array cannot contain more than 8 items.

What it means

EmailAction.Attachments models the underlying IEmailAction attachments list, which Windows Task Scheduler caps at 8 items. Setting more than 8 throws ArgumentOutOfRangeException before the value reaches COM. The cap mirrors the native Task Scheduler restriction (V1 8-item cap enforced by the library).

Source

Thrown at winPEAS/winPEASexe/winPEAS/TaskScheduler/Action.cs:456

            {
            }

            /// <summary>
            /// Gets or sets an array of file paths to be sent as attachments with the e-mail. Each item must be a <see cref="string"/> value
            /// containing a path to file.
            /// </summary>
            [XmlArray("Attachments", IsNullable = true)]
            [XmlArrayItem("File", typeof(string))]
            [DefaultValue(null)]
            public object[] Attachments
            {
                get => GetProperty<object[], IEmailAction>(nameof(Attachments));
                set
                {
                    if (value != null)
                    {
                        if (value.Length > 8)
                            throw new ArgumentOutOfRangeException(nameof(Attachments), @"Attachments array cannot contain more than 8 items.");
                        if (validateAttachments)
                        {
                            foreach (var o in value)
                                if (!(o is string) || !System.IO.File.Exists((string)o))
                                    throw new ArgumentException(@"Each value of the array must contain a valid file reference.", nameof(Attachments));
                        }
                    }
                    if (iAction == null && (value == null || value.Length == 0))
                    {
                        unboundValues.Remove(nameof(Attachments));
                        OnPropertyChanged(nameof(Attachments));
                    }
                    else
                        SetProperty<object[], IEmailAction>(nameof(Attachments), value);
                }
            }

            /// <summary>Gets or sets the e-mail address or addresses that you want to Bcc in the e-mail.</summary>

View on GitHub (pinned to 53fb989abc)

Solutions

Limit the Attachments array to 8 entries; attach remaining files via a zip archive or a link instead
Validate the array length before assigning and split into multiple email actions if needed
Zip the files and attach the single archive when more than 8 files must be sent
Catch ArgumentOutOfRangeException around the property set to give a user-friendly message

Example fix

// before
emailAction.Attachments = allLogFiles; // may exceed 8
// after
emailAction.Attachments = allLogFiles.Take(8).ToArray();

Defensive patterns

Strategy: validation

Validate before calling

static bool AttachmentsWithinLimit(object[] a) => a == null || a.Length <= 8;

Try / catch

try { emailAction.Attachments = files; }
catch (ArgumentOutOfRangeException)
{
    log.Error("Email action supports at most 8 attachments; zip files or split the alert.");
}

Prevention

Truncate or chunk attachment lists to 8 items max
Zip many files into one archive and attach that
Validate array length before assignment, not at registration time
Split high-volume notifications into multiple email actions

When it happens

Trigger: Assigning an object[]/string[] with 9+ file paths to the Attachments property, either directly or via constructor/config loading of an email action.

Common situations: Bulk-report tasks attaching many log files; generated alerts attaching all files in a directory; importing older task XML with a large attachment list.

Related errors

AI-assisted analysis of peass-ng/PEASS-ng@53fb989abc (2026-09-02). Data as JSON: /api/errors/6431d2cff9aa85a3. Report an issue: GitHub.