Getting "Unexpected error while performing an AJAX call. Maybe the connection to the server is lost" on register

I have installed Elgg 1.12 in my GoDaddy hosting. The site was working fine until yesterday. Now, whenever anyone tries to register, clicking on the registration link on the login page, it is showing a bunch of error messages as "Unexpected error while performing an AJAX call. Maybe the connection to the server is lost" 

I have tried checking the error log file, but no error is being shown.... The php version is 5.4.45.

Can anyone tell me why is this error being shown? Although, the registration is going fine...