Zoho books client portal from mobile

Zoho books client portal from mobile

Hi,
I noticed that my customers are not being able to log in to my zoho client portal. Whenever they enters the details and click sign in a error message says error occurred. Any idea how to fix it?
      Even I tried to log in the client portal, and encountered the same issue. I was using Android 7.0 nougat and Google Chrome. Thank you, hope I will get help to fix that issue soon.