Quick Fix Solution:  Try DXF format import or export as an alternative.  Essentially DXF is the ASCII/Text version of DWG files.  Any CAD software that can support a DWG file, should be able to handle DXF.

Linux Users:   DWG import/export is not available on Linux.   You will only be able to handle DXF files.

ACE uses an external COM file (ActiveConverter64.dll) to generate DWG files.  During installation of ACE, the installer will automatically attempt to register the external COM file, however it's possible due to limited user permission, UAC disabled (or other reasons) that  ActiveConverter64.dll was not properly registered on your computer.  You can manually register the COM file using the command prompt - see below for complete instructions:

How to manually register a DLL

A DLL file is a module containing certain functions that can be used by multiple programs as long as it is registered. Please follow the steps below to manually register a DLL file. 

Windows Server 2012,  Windows 8, Windows Server 2012 R2, Windows 8.1, or Windows 10:

1. The Start button is hidden in these versions of Windows.  To see the Start button, move and hover your cursor over the lower left corner of  the desktop where the Start button was in previous versions of Windows.
2. Right-click on the Start button that appears, you will see a menu. Select Command Prompt (Admin).
3. You will see the command prompt window open with the wording "Administrator: Command Prompt" at the top of the Window.
4. At the command prompt, enter: REGSVR32 "PATH TO THE DLL FILE" 

           Example: How to register the ActiveConverter.dll file: 

           REGSVR32 "C:\Numerical Innovations\ACE3000V8\bin\ActiveConverter.dll"

           If using a 64-bit operating system, then the command would be: 

           C:\Windows\SysWOW64\REGSVR32 "C:\Numerical Innovations\ACE3000V8_64\bin\ActiveConverter64.dll" 

Note: Be sure to include the quotation marks if the path contains any spaces.

Windows 7, Windows Server 2008 or Windows Server 2008 R2:

If User Account Control (UAC) is enabled, then you will need to register the DLL file from an elevated Command prompt by completing the following steps:

1. Click Start > All Programs > Accessories and right-click on "Command Prompt" and select "Run as Administrator" OR in the Search box, type CMD and when cmd.exe appears in your results, right-click on cmd.exe and select "Run as administrator"
2. At the command prompt, enter: REGSVR32 "PATH TO THE DLL FILE" 

           Example: How to register the ActiveConverter.dll file: 

           REGSVR32 "C:\Numerical Innovations\ACE3000V8\bin\ActiveConverter.dll"

           If using a 64-bit operating system, then the command would be: 

           C:\Windows\SysWOW64\REGSVR32 "C:\Numerical Innovations\ ACE3000V8_64 \bin\ActiveConverter64.dll" 

Note: Be sure to include the quotation marks if the path contains any spaces.

If User Account Control (UAC) is disabled, then complete the following:

1. Press and hold the Windows key then press R. 
2. Enter cmd in the Run line and click OK. 
3. At the command prompt, enter: REGSVR32 "PATH TO THE DLL FILE"
   
   Example 1: How to register the ActiveConverter.dll file:
   REGSVR32 "C:\Numerical Innovations\ACE3000V8\bin\ActiveConverter.dll"
   If using a 64-bit operating system, then the command would be:
   C:\Windows\SysWOW64\REGSVR32 "C:\Numerical Innovations\ ACE3000V8_64 \bin\ActiveConverter64.dll"
   Note: Be sure to include the quotation marks if the path contains any spaces.
   
   Example 2: How to register a system file:
   REGSVR32 C:\Windows\System32\example.dll
   If using a 64-bit operating system, then the command would be:
   C:\Windows\SysWOW64\REGSVR32 C:\Windows\SysWOW64\example.dll
    
4. Click OK. 

OR 

1. Click Start, Run or press and hold the Windows key then press R. 

2. Type REGSVR32 in the Run line 

3. Press the Space button on the keyboard

4. From the file location of the .dll file, select/highlight the pertinent .dll file

5. Drag and drop the selected/highlighted .dll file into the Run line after the space (Sample command: REGSVR32 C:\Numerical Innovations\ ACE3000V8_64 \bin\ActiveConverter64.dll")
   Note:  Be sure to include the quotation marks if the path contains any spaces.

6. Click OK