Converted tables to charts but API link fails generate image

The Charts i have just converted from tables cannot be generated as images,
the API link clicked has to generate an image to be downloaded. but for these links it gives this error_

HTTP Status 500 -

···

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

	org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Double org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:978) org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:857) javax.servlet.http.HttpServlet.service(HttpServlet.java:621) org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:842) javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

and a lot more down.
where am I going wrong?
thank you in advance.