Intername error:41-1 when upgrading in Nav 2015

Hi,
We have a customer on Nav 2015 Cu 11, build 42603.
I have done a SQL backup and restored to our dev system.
Opened the database in Dev Env and got msg that database needs to be converted.
Click ok and then got error "There are errors in the text file conversion text no. 1810-11 does not exist in the .stx file. Internal error:47-1" - See screenshot attached.

So cannot sync the objects.

The Cronus database opens ok.

Help !!!!
<img src="http://cd8ba0b44a15c10065fd-24461f391e20b7336331d5789078af53.r23.cf1.rackcdn.com/vadysoft-mibuso.vanillaforums.com/FileUpload/45/d24d6df9d41de6d78c6677888279be.png&quot; />