How to Automatically Load AutoLISP Scripts in AutoCAD (Startup Suite Guide – AutoCAD 2025/2026/2027)

ByCADAuthority Team

If you want AutoCAD to automatically load AutoLISP scripts at startup, the Startup Suite is the most reliable method to keep your environment consistent across drawings. No manual loading, no missed tools — your routines are available every time a drawing opens.

This guide covers the exact setup, how it behaves under the hood, and what typically breaks in real production setups.

What Is the AutoCAD Startup Suite?

The Startup Suite is part of the APPLOAD mechanism. It allows you to define a list of AutoLISP files (.lsp, .fas, .vlx) that AutoCAD loads automatically.

Key point that many users miss:

  • The Startup Suite loads scripts into every drawing that opens, not just once at application startup
  • In that sense, it behaves more like a visual version of acaddoc.lsp, not acad.lsp

This makes it ideal for:

  • Standard toolsets across projects
  • Multi-drawing workflows
  • Small teams without full deployment infrastructure

Step-by-Step: Add AutoLISP to Startup Suite (AutoCAD 2025/2026)

1. Access the Load/Unload Applications Dialog

The Startup Suite is inside the standard loading interface.

  • Type APPLOAD (or AP) in the command line and press Enter
  • Or go to Manage tab → Load Application

2. Locate the Startup Suite

In the bottom-right corner of the dialog box:

  • Find Startup Suite
  • Click Contents…

3. Add Your Scripts

In the Startup Suite dialog:

  • Click Add…
  • Navigate to your .lsp, .fas, or .vlx files

Pro Tip: Use a permanent folder, for example:

C:\CAD_Standards\Lisp\

If files are moved later, AutoCAD will not throw a blocking error — it will simply ignore them (silent fail).

  • Select your files → Open
  • Confirm they appear in the list

4. Optional: Use “Add to History”

Inside APPLOAD, you can check “Add to History”.

Use this when:

  • You don’t want auto-load
  • But you need quick access to frequently used scripts

This avoids re-browsing folders every time.

5. Close and Verify

  • Close both dialogs

Test properly:

  • Restart AutoCAD OR open a new drawing
  • Watch the command line for load messages

Verify That AutoLISP Is Loading Correctly

Do not assume it works.

Use a simple confirmation inside your script:

(prompt "\nMy LISP Loaded Successfully.")

Then:

  • Open a new drawing
  • Confirm the message appears

If not, the script didn’t load.

Common Issues and Fixes (Field-Proven)

1. Script Not Loading

Check:

  • File path still valid
  • File extension correct (.lsp vs .txt)
  • Script added to Startup Suite (not just loaded once via APPLOAD)

2. Silent Fail (Most Common Issue)

If a file is moved or deleted:

  • AutoCAD often does not show a blocking error
  • The entry remains in the list, but is ignored

Fix:

  • Reopen Startup Suite → Contents
  • Clean invalid paths regularly

3. Blocked by Security (SECURELOAD)

AutoCAD uses the SECURELOAD system variable:

  • 0 → loads everything (not recommended)
  • 1 → prompts user
  • 2 → blocks untrusted files

Fix:

  • Type OPTIONS
  • Go to Files → Trusted Locations
  • Add your LISP folder

Reference: https://help.autodesk.com/view/ACD/2025/ENU/?guid=GUID-TrustedLocations

4. Works Once, Then Stops

Typical causes:

  • File moved
  • Network path unavailable at startup
  • Dependency missing

5. Slow Startup

Too many scripts loaded at once:

  • Keep Startup Suite lean
  • Move heavy routines to manual or conditional load

6. Script Runs Too Early

Some scripts require a fully initialized drawing.

Fix:

  • Move logic to acaddoc.lsp
  • Or delay execution inside the LISP

Order of Loading (Important for Conflicts)

If multiple mechanisms are used:

  1. acaddoc.lsp loads first
  2. Startup Suite loads after

If the same function is defined twice:

  • The later load (Startup Suite) overrides the earlier one

This is a common source of conflicts in mixed setups.

Startup Suite vs acad.lsp vs acaddoc.lsp

Startup Suite

  • Loads for each drawing
  • Visual and easy to manage
  • Equivalent behavior to acaddoc.lsp
  • Best for individuals and small teams

acad.lsp

  • Loads once per AutoCAD session
  • Good for global definitions
  • Does NOT reload per drawing

acaddoc.lsp

  • Loads for every drawing
  • Required for drawing-level automation
  • Preferred for structured deployments

Reference: https://help.autodesk.com/view/ACD/2025/ENU/?guid=GUID-AcadLispFiles

Alternative for CAD Managers: CUI / Enterprise Setup

For larger environments:

  • Load LISP through CUI/CUIx customization files
  • Attach scripts to commands, menus, or tool palettes

Advantages:

  • Tied to user profile
  • Easier to standardize across teams
  • Cleaner than maintaining local Startup Suite lists

Best Practices for AutoLISP Management

  • Use a central, stable folder structure
  • Avoid Desktop or temporary paths
  • Keep filenames consistent
  • Separate:
    • production scripts
    • test scripts

For teams:

  • Use network paths
  • Add them to Support File Search Path
  • Expect latency — test performance

Example: Minimal AutoLISP Test Script

(defun c:testload ()
  (prompt "\nAutoLISP is working correctly.")
  (princ)
)
(prompt "\nTest LISP Loaded.")

After restart:

  • Type TESTLOAD
  • If it runs, your setup is valid

Advanced Notes (Production Use)

  • Avoid loading full libraries at startup unless required
  • Use autoload patterns where possible
  • Combine Startup Suite with CUI deployment for scale
  • Monitor network-based scripts for delays

FAQ – AutoCAD AutoLISP Startup Suite

Why is my AutoLISP not loading automatically?

Most common causes:

  • Folder not in Trusted Locations
  • File moved (silent fail)
  • Not added to Startup Suite
  • Blocked by SECURELOAD

Where should I store AutoLISP files?

Use a permanent path:

C:\CAD_Standards\Lisp\

For teams:

  • Shared network folder
  • Added to Support File Search Path

What is the difference between APPLOAD and Startup Suite?

  • APPLOAD = manual load
  • Startup Suite = automatic load per drawing

Should I use Startup Suite or acaddoc.lsp?

  • Use Startup Suite for simplicity
  • Use acaddoc.lsp for:
    • controlled environments
    • dependency management
    • enterprise workflows

Can I load multiple LISP files automatically?

Yes.

But:

  • Too many files = slower startup
  • Keep only essential scripts

Does this work on AutoCAD for Mac?

Yes, but behavior differs.

On Mac:

  • Use APPLOAD
  • There is no “briefcase” Startup Suite UI
  • Instead, enable “Auto-load” checkbox next to each file

Reference: https://help.autodesk.com/view/ACD/2025/ENU/?guid=GUID-MacAutoLisp

Why does my script work manually but not at startup?

Usually:

  • It executes too early
  • It depends on drawing context
  • It requires delayed execution or acaddoc.lsp

How do I create my first .lsp file?

If you’re starting from scratch, refer to your internal guide or documentation on creating AutoLISP scripts. This is typically covered in beginner AutoLISP tutorials and should be linked here for continuity.

Final Check (Quick Validation)

Before calling it done:

  • Scripts stored in stable folder
  • Path added to Trusted Locations
  • Files listed in Startup Suite
  • Tested on new drawing
  • No dead paths in list

Once this is clean, your AutoCAD AutoLISP autoload setup will behave predictably across sessions and drawings.

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