Commands

APPLOAD command in AutoCAD : Loads and unloads applications and defines which applications to load at startup

If you need to load third‑party routines, AutoLISP files or compiled modules into AutoCAD, the appload command is the built‑in tool that lets you do that quickly and control which applications start with AutoCAD. This guide explains what APPLOAD does, how to use it step‑by‑step, alternatives, common errors and fixes, and practical tips for reliable loading and startup automation.

What is the APPLOAD command?

APPLOAD is an AutoCAD command that loads and unloads external applications and scripts (for example AutoLISP, Visual LISP, ARX, and .NET assemblies) and lets you define which applications load at AutoCAD startup. Use it to:

  • Temporarily load an application for the current session.
  • Add files to the Startup Suite so they automatically load when AutoCAD starts.
  • Unload or remove applications when they are no longer needed.

Supported file types commonly loaded through APPLOAD include .lsp, .fas, .vlx, .arx and sometimes .dll (note: .NET assemblies are typically loaded with NETLOAD).

File types and when to use them

  • .lsp — Plain AutoLISP source files. Editable and easy to load with APPLOAD or VLIDE.
  • .fas / .vlx — Compiled AutoLISP/Visual LISP files (faster, protected source).
  • .arx — ObjectARX modules (compiled C++ plugins). Often used for advanced features.
  • .dll (.NET) — .NET assemblies; prefer NETLOAD for these, though APPLOAD may work with some.
  • .arx/.dbx — database extensions loaded for specific tasks.
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Always check the documentation for the specific plugin to know the recommended loading method.

How to use appload (Step by step)

Quick command

  1. At the Command prompt type:
    appload
    and press Enter.

Or use the Ribbon

  1. Open the Manage tab.
  2. In the Applications panel click load application (this opens the Load/Unload Applications dialog — the APPLOAD interface).

APPLOAD dialog — basic steps

  1. In the Load/Unload Applications dialog click Contents to open the Startup Suite, or click Load to load a file for the current session only.
  2. Navigate to the folder where your file is stored.
  3. Select the file (for example mytools.lsp or plugin.vlx) and click Open.
  4. If you want it to load every time AutoCAD starts, click Contents, then Add, browse to the file and add it to the Startup Suite.
  5. Close the dialog. The routines are now loaded for the session (and on startup if added to the Startup Suite).

Using VLIDE for LISP development

  • Open the Visual LISP Editor (VLIDE) and use File > Load to load .lsp files. VLIDE provides debugging and is ideal for development.

Short example

  • Problem: A custom command DEFUN “C:MYCMD” in mytools.lsp is not available.
  • Solution: Type appload → Load → select mytools.lsp → Close. Now type MYCMD and run the custom command.

Using the Startup Suite vs support paths and LISP auto‑load

  • Startup Suite (APPLOAD > Contents) — Recommended for a small set of routines you want every session. Files placed here are explicitly loaded at startup.
  • Support File Search Path (Options > Files > Support File Search Path) — Place frequently used files in a folder listed here. AutoCAD will find them when required (e.g., by SCRIPT, lisp that does (load “file”) ).
  • acad.lsp / acaddoc.lsp — Legacy method: placing AutoLISP routines in these files (in a folder on the support path) ensures they load automatically. Use acaddoc.lsp for document-specific startup; use acad.lsp for application-level startup. Note: modern AutoCAD versions favor the Startup Suite and trusted locations.
  • NETLOAD — Use this command to load .NET assemblies (.dll) built for AutoCAD.
  • Command line / script — You can add a load line in a startup script: (load “mytools”) executed via acaddoc.lsp or script at startup.
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Common reasons appload doesn’t work and how to fix them

  1. File is blocked by Windows

    • Symptoms: File won’t load, or you get an error indicating file is blocked.
    • Fix: Right‑click the file in Windows Explorer → Properties → if you see “Unblock”, check it and Apply.

  2. Not a trusted location (Security/Trusted Paths)

    • Symptoms: AutoCAD refuses to run LISP/VBA or warns on load.
    • Fix: Add the folder to Trusted Locations (Options > Files > Trusted Locations) or disable certain security checks carefully (not recommended).

  3. 32‑bit vs 64‑bit mismatch

    • Symptoms: .arx or .dll fails to load with architecture error.
    • Fix: Ensure the plugin was compiled for the same architecture/version of AutoCAD you are running.

  4. Missing dependencies

    • Symptoms: Module loads partially or throws runtime errors.
    • Fix: Check documentation for required libraries and ensure they are installed and available in the support path or same folder.

  5. Corrupt or incompatible file

    • Fix: Re-download or recompile the plugin; test a known working plugin to confirm APPLOAD is functional.

  6. Permission or antivirus blocking

    • Symptoms: Load fails silently or antivirus flags the file.
    • Fix: Temporarily disable antivirus for testing or add an exclusion. Ensure you trust the file source before doing so.

  7. Wrong command to load the module

    • Symptom: Trying to use NETLOAD for AutoLISP or APPLOAD for .NET causing confusion.
    • Fix: Use the recommended loader: APPLOAD for .lsp/.fas/.vlx/.arx, NETLOAD for .NET .dll assemblies, VLIDE for development.

  8. Routines not added to Startup Suite

    • Symptom: Loaded routines work in the current session but are gone after restart.
    • Fix: Add the file to the Startup Suite in the APPLOAD dialog or place it in a trusted folder on the Support File Search Path.

Alternative methods to load code

  • NETLOAD — For loading .NET assemblies (.dll) built for AutoCAD. Usage: Type NETLOAD, select DLL.
  • Put LISP in Support Path — Files on the Support File Search Path can be loaded by (load “name”) without full path.
  • acad.lsp / acaddoc.lsp — Add (load “…”) commands to these files to auto-run code at startup.
  • AutoCAD Startup Scripts — Use scripts or registry settings for enterprise deployments.
  • Deployment / Installer — For distributed plugins, create an installer that sets trusted locations, adds plugins to the Startup Suite, and registers components.
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Practical tips and best practices

  • Always backup AutoCAD support folders before changing startup scripts.
  • Keep third‑party routines in a dedicated folder and add that folder to Trusted Locations.
  • For development use VLIDE — it provides debugging, breakpoints, and step execution.
  • Prefer compiled versions (.fas/.vlx) for distribution to protect source code and increase performance.
  • Document which versions of AutoCAD a plugin supports; tie that into your support path and startup setup.
  • Test plugins in a clean profile or sandboxed drawing to avoid conflicts with other routines.
  • When adding items to the Startup Suite, keep the list small to avoid slow startup times.

FAQ

How do I make an AutoLISP file load automatically every time AutoCAD starts?

Add the file to the Startup Suite via APPLOAD > Contents > Add, or place a (load “yourfile”) call inside acaddoc.lsp or acad.lsp located in a folder on the Support File Search Path. Also add the folder to Trusted Locations to avoid security blocks.

Can I use APPLOAD to load .NET DLLs?

You can sometimes load DLLs with APPLOAD, but the recommended approach for .NET assemblies is to use the NETLOAD command, which is designed for managed .dlls built against the AutoCAD .NET API.

My LISP file loads but custom commands return “unknown command.” Why?

Possible reasons: the LISP didn’t define commands as expected, it failed to load completely due to errors, or the command name requires a prefix (like C:). Check the Command window for load errors and test in VLIDE to debug.

Why does AutoCAD warn about untrusted files when loading LISP?

AutoCAD has security settings to protect against unauthorized code. Add your plugin folder to Trusted Locations (Options > Files > Trusted Locations) or sign your code using a trusted publisher if distributing widely.

How can I check which applications are currently loaded?

Type APPLOAD and review the Loaded Applications list, or check the Startup Suite contents. You can also inspect the console for messages and use the Visual LISP environment to list loaded functions.

My .arx/.dll won’t load — it says “bad format” or “wrong architecture.” What do I do?

This indicates a 32/64-bit mismatch or a build for a different AutoCAD version. Obtain the correct build of the plugin compiled for your AutoCAD version and platform.

Is it safe to add many files to the Startup Suite?

Adding many files can slow AutoCAD startup and increase the risk of conflicts. Only add trusted, necessary routines. For many users or enterprise setups, manage startup loading through a controlled deployment process.

How do I unload a plugin once loaded?

Open APPLOAD, select the loaded module and click Unload (or use the module’s unloading routine if provided). For .NET assemblies use the plugin’s uninstall method or restart AutoCAD if the module cannot be unloaded cleanly.

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