As an existing AutoCAD LT95 user, you most likely cannot do without your beloved AutoCAD. With the latest hardware and required move to new Windows versions, trying to install your AutoCAD LT95 gives an error like this one…

“This app can’t run on your PC”

or this one…

Ransomware Protection Windows 11 and AutoCAD

Just before we start note that Windows 11 comes with a Ransomware Protection which includes Controlled Folder Access. Controlled folder access blocks applications from writing to your Documents, Pictures, Videos, Music, Public and Favorites folders. AutoCAD versions all the way to AutoCAD 2021 write to certain user Public folders and are therefore blocked by this feature. This can cause issues with all sorts of things including activating your AutoCAD license and even running AutoCAD. Ransomware Protection is an important feature of Windows 11 but it will affect your AutoCAD unless you allow AutoCAD and its dependent applications access to the controlled folders.

How to install AutoCAD LT95

A quick word of advice: please follow the instructions below precisely as documented including using the same folder names and paths. This will significantly reduce the risk of having any problems…

1. If you don’t yet have a copy of the Longbow Converter App you can purchase it here or click on the download link we sent you via email in order to download the Converter App to your PC.
2. Before installing the Converter App, make sure the files downloaded from our site are not blocked by Windows SmartScreen… Windows 11 is finicky, click the TLC zip first to make sure it’s fully selected then Right+click the file and select Properties. Be sure to check the Unblock checkbox as shown below and Click OK…

3. Double click the zip file to open it and install the TLC application as normal. By the way, TLC stands for The Longbow Converter
4. Once installed, start the Longbow Converter App…
   1. Now place your AutoCAD LT95 CD in the CDRom Drive
   2. In the Converter App, select the 2nd tab named “Old AutoCAD Installer Reviver“
   3. Using the “. . .” button, select your AutoCAD LT95 installation CD
   4. Next, click the “Run Old Installer” button and follow the onscreen instructions. If all is well a dialog will appear stating success, simply click OK to start your AutoCAD setup
      1. Now I know it’s unheard of these days, but at this point expect to wait up to 45 minutes for your AutoCAD LT95 setup.exe program to appear, be patient – NOTE: do not continue with the install until reading the next step…
   5. Once the setup starts, stop and read the next steps all the way to the end! By the way, if your AutoCAD LT95 setup does not start after 45 minutes, read the Troubleshooting section below.
5. In the AutoCAD LT95 setup program…
   1. navigate through each setup dialog as normal, with these exceptions…
   2. Make sure you do a Typical Install (not a Full Install)
   3. When you get to the installation folder input dialog **it’s vitally important to make sure you install to c:\acadLT95 (not Program Files\AutoCAD LT95 as usually prompted)**
6. Now carry on with the install
   1. Do not reboot once the install is complete
   2. Ignore any errors related to not being able to create the shortcut e.g. “Cannot Create folder ‘AutoCAD LT95’“, you will have to create a shortcut on your computer Desktop to your c:\acadLT95\acad.exe by hand.
   3. Again, do not reboot if prompted to do so
7. Once your AutoCAD LT95 setup has completed the installation…
   1. Make sure you fully close the setup program.
   2. Once the setup is closed the Converter will automatically fix the c:\acadLT95 program files. You should see “Success!” displayed in the 3rd tab named “Old AutoCAD Program Reviver“
   3. Now reboot your PC
8. You can now run your AutoCAD LT95, using Windows Explorer, navigate to c:\acadLT95 and double click aclt.exe

Troubleshooting

• If your AutoCAD setup is not starting after 45 minutes…
  1. First try turning off UAC, rebooting, then restart the steps above.
  2. If it is still failing, most likely it’s because of another application on your system which is preventing our setup routine from starting (perhaps anti-virus, or similar) – try installing LT95 from Windows Safe Mode
• If you are getting either a Bad Mem Pointer error and or a Smartheap handler recursively re-entered error when you start your AutoCAD then you need to re-run all the steps above, taking care to do each step precisely as it says, most likely you are missing from step 5 or you have not installed to c:\acadLT95 as stated in step (7) above.
• When starting AutoCAD, if you receive an ‘acad.exe – System Error’ message: The program can’t start because ac1st15.dll is missing from your computer. Try reinstalling the program to fix this problem. If you carried out step (7) above, then try rebooting your PC
• If you are getting a WinHelp() error when pressing F1 to try and access the Help system then simply install the WinHelp (WinHlp32.exe) module from Microsoft
• Issues with Calcomp Digitizer – Calcomp Digitizer not working
• If the setup displays an error message InstallError (IUO)               
  (X)  not enough space(IUO) try unplugging any External USB drives
• Plotting issues? If you get an error splwow64.exe “The application was unable to start correctly” with error “0xc0000005”
  1. Make sure your Anti-virus and/or Windows Firewall is not blocking splwow64.exe
  2. If the problem persists
     1. First, note that you need the latest version of the Converter App
     2. Start the Converter App
     3. Select the 3d tab “Old AutoCAD Program Reviver” 
     4. Click the Tools Menu->Reduced Power Mode
     5. Using the “…” button, pick your acad.exe folder e.g. c:\acadLT95
     6. Click “Fix Old Program” and follow prompts
• If you have crashing problems using the File->Open or File->Save dialogs inside of AutoCAD please read this blog entry on the File->Open or File->Save Crash in AutoCAD

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