Reason 1

Just installed C-PEN Core and it does not start properly?

Is there a “OCR is missing ” error message?

The later versions of C-PEN Core uses a newer version of the OCR engine (Optical Character Recognition) and if a previous version of C-PEN Core has been installed and not properly removed – then the new OCR is not properly installed. If this happens, or the OCR is not properly installed for any other reason this message is shown.

To resolve it we need to make sure that any old OCR is removed and the new (which is included in the C-PEN Core installer) is installed.

These steps apply to Windows 10 but are pretty similar for earlier versions of Windows.

  1. Go to Windows Settings\Apps and Features
  2. Use the search list and search for OCR.
  3. If C-Pen OCR Engine shows up – chose to uninstall it.
  4. Now download and reinstall latest C-PEN Core version.


If required, please consult How to make a clean re-install article.


Reason 2

.NET 3.5 and .NET 4.7.2 are not installed


How to install .NET 3.5 & 4.7.2

  1. Open Control Panel.
  2. Select Program and Features.
  3. Select Turn Windows features on and off.
  4. Find and select the checkbox .NET Framework 3.5 (includes .NET 2.0 and 3.0).
  5. Find and select the checkbox .NET Framework 4.8 Advanced Service.
  6. Click OK to confirm and install.


For more details, see Installing .NET 3.5 on Windows