I have edited the printable form (Top > Configuration Director > Miscellaneous Settings > Printable Forms > Printable Forms) and saved it. Now if I am trying to edit it again, the source page is blank.
The source cannot be uploaded due to the incorrect spelling, e.g. '
</br>' is used instead of '
<br />' and etc.
Check all the symbols in the form. Remove the existing form and create a new one with the correct spelling.