Есть вот такая инфа, с похожими симптомами:
Certain Preps 5 templates will not open in Preps 6 or later
Symptoms
When trying to open certain Preps templates built in Preps 5 you get an error message and the template fails to open.
Product
Preps 6 and later
Operating System
Any
Error message
Cannot open this template file
Reason: UNEXPECTED_TOKEN
Error token: %SSiSignature:
Cause
In Preps 5 you could accidentally create a Signature that did not have a signature in it. This would be like opening an existing Preps template and deleting the imposition and stock and media from it and trying to save. That will crash Preps.
Solution
Option 1 (performed in Preps 6 or later)
To find the line number where the error happens, open the .tpl file in Preps 6 or later.
Open the .tpl file in a text editor and go to the line where the error happens.
If that line and the line above it start with %SSiSignature, delete the line above the referenced line. For example, if the referenced line is line10, delete line 9.
Option 2 (performed in Preps 5.x)
Open the template in Preps 5.x, delete the empty signature, then resave the template.