is it compulsory to upload a photo with white background in the CAT form?

Well, as per the guidelines that are given in the application form, it is highly recommended that you upload photograph with white background. This is advised to be done because it gives the best contrast of the photograph as a lighter background won't hinder your real picture much and it appears to be soothing. However as the forms might already be filled long back and with just two more days remaining for CAT, even if by mistake you had uploaded a photo with a different background, do not worry. You might have already got your admit card. Take 4-5 print outs of the same, paste the same photograph that you had uploaded and go with a cool mind. In the examination Hall, the invigilator or the examination in charge, will anyway take another picture of every candidate.
All the best!!