An error message appears stating ‘Invalid NBS File Format’. When clicking OK to this message “The selected document could not be opened” is displayed. Click OK and the document does not open.

NBS Spec KB10067_2


This may occur if NBS Building or NBS Landscape closes irregularly e.g. due to a power cut or system crash etc.


In order to resolve this issue, you can use the back-up of the file which is automatically created:
  1.     Browse to the location of your specification
  2.     Right click on the backup version of the file, select Rename and change the file extension from .bak to .spec
  3.     Now double left click on this file, and it should open.

In a very few circumstances the back-up file will also be corrupt. In cases like these, use the repair function within the software. To access this function, click on Tools > Compact Specification and you will be prompted with the following window:




Browse to the corrupt file and click OK. A message stating that the file has been successfully repaired will be displayed and the file can now be opened.

If the software still can’t load you specification, please contact the NBS Customer Support team on 0345 456 9594, or email the corrupt specification file to