Server Error

I have prepared a Excel Format of a survey consisting 824 questions for Kobo Toolbox. While the file is being replaced successfully every time after update, it is not being redeployed and showing error ‘Server Error (500)’ . It is to be noted that the same file format was redeployed successfully last day! Please suggest me what measure I can take to overcome this problem.

After replacement Just refresh (F5 in web browser) the page. you will see deployment warning
“If you want to make these changes public, you must deploy this form.”
now you can redeploy your form…

Can you share some screenshot?