→ Private area
Aplitop · Surveying the Future
Support Center

Support

Error "Class not registered", "Cannot open file CargadorNet.dll" or "Unknown error 0x80131700": missing system dependencies (.NET / Visual C++)

Updated on

Summary

Some MDT modules depend on operating system components: the Microsoft Visual C++ redistributables and the .NET Framework. When one of them is missing or damaged —a common situation on new computers or after an installation that did not finish properly— certain commands fail with messages such as "Class not registered", "Cannot open file CargadorNet.dll" or "Unknown error 0x80131700", or the installer itself warns that a component is missing. The solution is to install or repair the right dependency, and the files you need ship inside the MDT installation folder itself. If the error does not name any of these components and what fails is the installer, see How to resolve issues with the MDT 26 installer.

Applies to

  • MDT — applies to MDT 9, MDT 25 and MDT 26. The paths of the redistributables (Runtimes\x64) are documented in the MDT 9 and MDT 25 cases; on MDT 26 the two steps that solve most cases are verified: running Dep2.exe from the bin subfolder and enabling .NET Framework 3.5.

  • CAD: AutoCAD (cases with 2021, 2025 and 2026), ZWCAD 2025, GstarCAD 2026.

Symptoms

  • Running commands such as Edit Point, Change Format of points or Insert WMS image shows the message "Class not registered" (sometimes together with "unknown error"), even when the CAD is run as administrator.

  • The error "Cannot open file CargadorNet.dll" appears.

  • Changing the format of the points (MDT > Points > Modify Points > Change Format) shows "Unknown error 0x80131700"; in some cases the CAD freezes.

  • During installation on a new computer, the installer warns that the "Visual C++ Runtime 9.0 Service Pack 1" or other components are missing.

  • Some menus appear in English and the MDT point block cannot be edited (case documented with a damaged .NET Framework).

Cause

The affected modules depend on Windows components that are not present or were not installed properly:

  • Visual C++ redistributables: the MDT installer is designed to install them when they are missing, but it may fail to do so (for lack of privileges, for instance). Without them, the commands that use them return "Class not registered" or cannot load CargadorNet.dll.

  • .NET Framework: the point editing modules (PuntosMDT25.dll, for example) depend on the .NET Framework; if it is incomplete or damaged, you get error 0x80131700, "Class not registered", menus in English or failures when editing the point block.

Solution

Case: "Class not registered" or "Cannot open file CargadorNet.dll" when running commands

The redistributables you need ship in the MDT installation folder, in the Runtimes\x64 subfolder:

  1. Close the CAD and open File Explorer in the folder where you installed MDT (by default C:\Program Files (x86)\Aplitop\MDT25 or C:\Program Files (x86)\Aplitop\MDT9).

  2. Go into the Runtimes > x64 subfolders and install the matching redistributable: in the documented cases, vcredist2010_x64.exe for MDT25 and vcredist2008sp1.exe for MDT9.

  3. Restart the computer.

  4. If the "Class not registered" error persists, run the reg64 file (in the dotnet subfolder of the installation folder, for example C:\Program Files (x86)\Aplitop\MDT25\dotnet) with administrator privileges.

  5. Open the CAD and check that the command now works.

If the warning appears during installation on a new computer ("Visual C++ Runtime 9.0 Service Pack 1 is missing"):

  1. Download and install the Visual C++ 2008 SP1 redistributable (vcredist2008sp1.exe, available at http://soporte.aplitop.com/usuarios/runtimes_x86/vcredist2008sp1.exe). Support can also provide a package with the complete set of Visual C++ 9.0 SP1 libraries; in that case install all of them.

  2. Restart the computer and start MDT again.

Case: "Unknown error 0x80131700" when changing the format of the points

This error means that a Windows update the MDT installer tries to apply during installation is missing, and it may not have completed (usually for lack of privileges):

  1. Go into the bin subfolder of the installation folder and run the Dep2.exe file — for example C:\Program Files (x86)\Aplitop\MDT25\bin, or C:\Program Files (x86)\Aplitop\MDT26\bin on MDT 26. The pending update will be installed; when it finishes, try the command again. If a Windows Update window appears while running it, wait for the update process to finish.

  2. If that does not solve it, run reg64 (dotnet subfolder) with administrator privileges, as in the previous case.

  3. In one documented case support also advised installing vcredist2008sp1.exe from the Runtimes\x64 subfolder.

  4. If the error continues, the .NET Framework itself is most likely damaged: in the documented cases it was solved by uninstalling and reinstalling (or repairing) the .NET Frameworks of the computer, sometimes with support's help over a remote connection.

To diagnose this kind of error, support may ask you for the installation report: run MDT > About Tcp-MDT, press the Export button and send the file it generates.

Case: .NET Framework not properly installed (menus in English, point block editing, "Class not registered")

If MDT was installed without .NET Framework 3.5 enabled, or it became damaged, various errors may appear ("Class not registered" when changing colours, menus shown in English even after changing the language in MDT > Utilities > Configuration, or being unable to edit the point block):

  1. Enable .NET Framework 3.5 in Windows: press Start, type features and open Turn Windows features on or off; tick the first option (.NET Framework 3.5) and press OK. If Windows asks whether to download the files from the Internet, answer yes.

  2. With the Framework in place, uninstall MDT and perform a clean installation of the most up-to-date version: fully extract the ZIP you downloaded and run setup.exe from the extracted folder with Run as administrator, checking that the installer detects your CAD version. If the installer gives you trouble, see How to resolve issues with the MDT 26 installer.

  3. If the symptoms continue, repair or reinstall the .NET Frameworks of the computer: in the documented cases this solved the problem for good.

If the problem persists

  • Run MDT > About Tcp-MDT > Export and send support the resulting file: with it they can check the state of your installation and tell you what to do next.

  • In one documented case, neither Dep2.exe nor a clean installation solved error 0x80131700, because a .NET Framework file was missing (possibly removed by the antivirus); support had to connect remotely to the computer and the user had to repair the .NET Frameworks. If you reach this point, contact support and tell them when you are available for a remote connection, with a user with administrator rights present. To keep the antivirus from interfering with a new installation, see ANTIVIRUS - Recommendations During MDT Installation.

Category: Installation and updates · Level: Intermediate

Type your question and pick a product to narrow the results. Use ↑ ↓ and Enter to open an article.