When I tried to update tripwire on a Debian Etch installation the other day it failed with the error:

  Interactive Update failed.      
### Error: Report file could not be parsed.  Report may be corrupt.        
### Exiting... 

I used the ordinary syntax to do the update, ie:

  tripwire --update --twrfile /var/lib/tripwire/report/server-YYYYMMDD-HHMMSS.twr

On another server it worked perfectly, the only difference is that they use different locales, so I tried running with another locale on the failing server:

 LC_ALL=C tripwire --update --twrfile /var/lib/tripwire/report/server-YYYYMMDD-HHMMSS.twr

Now it ran correctly.

For those of you who wonders, it was swedish UTF-8 locale on the failing system.