This appears to be an isolated issue.
1. If the 'TrPs printer is missing' message pops up on trying to export to PDF, do the following steps in order:
a. Install a recent version of PDF Creator (3.3 should be fine)- https://www.pdfforge.org/pdfcreator/download
b. Go to the registry \HKEY_LOCAL_MACHINE\SOFTWARE\Trace Software\DesignSpark Electrical\Services.
c. Create a new "String value" and name it "PSPrinterName" (without quotes). Then, set its value to " PDFCreator" (without quotes).
2. If you get this error message:
See if the GhostScript folder is present under the ProgramFiles directory of your DSE install.
If it is not, download, un-zip and place the extracted 'GhostScript' folder in the DSE installation path under ProgramFiles:
Re-start DSE, open a project and try exporting a schematic as PDF again.