@Rohit4 What is your aem version. Can you check your logs for any error. 

hi @DEBAL_DAS , I am able to add more than 40 TextField. I got this error once. After page reload it went. I am using AEM 6.5.8

Hi @Rohit4 ,You can add 40 or more fields. Sometimes, while adding fields you can get TooManyCallsException exception. Try to reload page/CF Model again. The screenshot you added says different error. Are you trying to save CF model without adding fields. Screenshot error says same. org.apache.sling...

Hi @Vani1012,Can you confirm if your page is loading. If yes, then check content tree.Go to - Top left icon in page. once window expand, click on third icon. Do you see your component there. As React SPA rendered client side, Clear your browser cache. Some time it is cached.