Unexpected token

1. What is the problem? Be very detailed.
When i upload xls form a red message appears so i can not see my form Preformatted text
The message is
Unexpected token in <JSON at position 0

What is the problem please


Hi Nedhal, I'm sorry to hear you are having this issue. Are you using Aggregate? If so, please note that Aggregate is no longer being supported. Central is now the ODK server. The post below has for more details about the end-of-life for Aggregate. Are you the administrator and have you considered upgrading to Central? Is there anything preventing your team from doing so?

The particular screenshot suggests that it's Central or XLSForm Online.

@nedhal The best way to get help is to upload the XLSForm and also tell us what URL to the server or service you are using.