In the Contact Center, using the Import/Export dropdown menu, an error after exporting your email as a PDF means one or more images in the template are too large for the system to compress into a PDF.
Exporting the HTML instead
Rather than inspecting and downsizing each image, select Export current HTML. This downloads a .txt file. Then use a third-party HTML-to-PDF converter to turn the HTML in that file into a PDF.
Tip: To find which image is causing the problem, remove images from the template one at a time and try the PDF export again after each.