Kees

Is this an imported project?

During the initial design/redesign of your project, you may have more joy if you can temporarily turn off responsive (step 2, Template, customisation, resolution and responsive design). Even minor changes can create a lot of work for WX5 with responsive turned on, potentially exhausting Windows resources.

My experience has been that when the desktop page content is effectively complete, turning on responsive is quite stable, especially when the blank cells have been filled with objects (although just before doing this I usually export the site to iwzip as a precaution).

You should also make frequent use of the backup now option (down arrow next to save)

Good luck - let us know if that helps or otherwise?

Hi Esahc..

Thank you for your answer. No, it is not an imported project. But i think you may be right. I turned responsive off for now and no errors occures. There were indeed a lot of cells without content. I will try again when the project is more or less finished. Thanks als for the back-up tip.

Hello Kees, 

I confirm that you receive this error because the program cannot calculate all the empty cells in the responsive mode. In order to solve this issue, you just have either to delete the empty cells or to insert an Object, also without editing it. 

Please let me know if I can be of any help. Kind regards.