Log Level

RevitDevTool uses standard System.Diagnostics.Trace output and assigns each entry a log level. The selected minimum level controls which messages are shown or written to the configured outputs.

Available levels

Level	Use it for
Trace	Very detailed diagnostic output
Debug	Development and troubleshooting details
Information	Normal progress and completed actions
Warning	Recoverable problems or unexpected conditions
Error	An operation failed but the host can continue
Critical	A severe failure requiring immediate attention

Configure the minimum level

Choose the minimum level in Settings → Log. Messages below that level are filtered from the logging pipeline. For normal use, Information is a good default; use Debug or Trace while investigating a problem.

Write log messages

Use the standard .NET trace APIs from C#, F#, Python.NET, IronPython, or a compatible add-in:

using System.Diagnostics;

Trace.TraceInformation("Export started");
Trace.TraceWarning("Room has no boundary");
Trace.TraceError("Export failed: {0}", exception.Message);
Debug.WriteLine("Detailed diagnostic value");

Python scripts can write through the same trace pipeline:

from System.Diagnostics import Trace

Trace.TraceInformation("Analysis started")
Trace.TraceWarning("Element was skipped")
Trace.TraceError("Analysis failed")

RevitDevTool also redirects supported Console.WriteLine and Python print() output into the trace pipeline. Use explicit trace methods when the severity matters.

IronPython on .NET 8 (Revit 2025 and later)

Revit 2025 and later run on .NET 8, where Trace and Console live in assemblies that IronPython does not load by default, such as the one pyRevit uses. Add the references before importing them:

ironpython_log_script.py

import clr
clr.AddReference("System.Diagnostics.TraceSource")
clr.AddReference("System.Console")

from System.Diagnostics import Debug, Trace
from System import Console

Trace.TraceInformation("Python script executed")
Trace.WriteLine("[WARN] Element not found")
Debug.WriteLine("Detailed diagnostic value")
Console.WriteLine("[INFO] Done")

• System.Diagnostics.TraceSource provides Trace.
• System.Console provides Console.
• Debug needs no reference on .NET 8.
• On Revit 2024 and earlier (.NET Framework 4.8) the references are not needed.

Debug or Trace in compiled add-ins

Debug.WriteLine is compiled only into Debug builds (the DEBUG constant), while Trace methods need the TRACE constant. Use Trace for messages that must also appear in a Release build.

How the level is chosen

Messages written with Trace.WriteLine, Console.WriteLine or print() carry no level of their own, so RevitDevTool reads it from the text:

1. Prefix: a bracketed tag at the start of the message is checked first.
2. Keywords: otherwise the message is scanned for level keywords, in the order Critical, Error, Warning, Information. The first match wins.
3. No match: the message is logged as Debug.

Level	Prefixes	Default keywords
Critical	[FATAL] [CRITICAL]	fatal, critical, crash
Error	[ERROR] [ERR]	error, failed, exception
Warning	[WARNING] [WARN]	warning, warn, caution
Information	[INFO] [INFORMATION]	info, success, completed
Debug	[DEBUG] [DBG]	none; the fallback

Short forms such as [FTL], [WRN] and [INF] also work, and [TRACE] or [VERBOSE] select the Trace level. Matching ignores case.

Trace.WriteLine("[WARN] Configuration not found, using defaults");   // Warning
Trace.WriteLine("Export completed");                                  // Information
Trace.WriteLine("Failed to process element 123456");                  // Error
Trace.WriteLine("Processing elements...");                            // Debug, no keyword matched

Change the keywords

Edit them in Settings → Log under Level Detection Keywords: comma-separated, up to 5 per level.

Ambiguous messages

A message that contains keywords for two levels takes the higher one, so Error handling completed is logged as Error. Add a prefix such as [INFO] when you want to be explicit.

Example: log an element's properties

Pick an element and log each of its properties at the right level. Properties that throw are logged as warnings instead of stopping the command:

ElementInfoCommand.cs

using System.Diagnostics;
using Autodesk.Revit.Attributes;
using Autodesk.Revit.DB;
using Autodesk.Revit.UI;
using Autodesk.Revit.UI.Selection;

[Transaction(TransactionMode.Manual)]
public class ElementInfoCommand : IExternalCommand
{
    public Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
    {
        var uidoc = commandData.Application.ActiveUIDocument;
        var reference = uidoc.Selection.PickObject(ObjectType.Element, "Select an element");
        var element = uidoc.Document.GetElement(reference);

        foreach (var property in element.GetType().GetProperties())
        {
            try
            {
                Trace.TraceInformation($"{property.Name}: {property.GetValue(element)}");
            }
            catch (Exception ex)
            {
                Trace.TraceWarning($"{property.Name} could not be read: {ex.Message}");
            }
        }

        return Result.Succeeded;
    }
}

What happens next

The level is applied before the message is delivered to the configured Log Output targets. Revit geometry objects written through the standard trace listener pipeline are handled by Geometry Visualization.

Related

• Log Output — Monitor, File, and HTTP destinations
• Geometry Visualization — transient geometry in Revit