It was working for several months, but one week ago, it failed.It seems strange that your chart suddenly stopped working a week ago. Are you sure nothing changed on your instance to cause this? When you run the page with Debug set to Yes, and click on the "Show XML" link under your chart region, does the XML appear correct or do you see any error messages?
The chart is a 2D Bar chart that uses an “Area” series. A custom call (xml) to the AnyChart plugin was used to create the chart, without using an Apex wizard.The fact that you have generated an “Area” series for your chart is an issue. The Application Express AnyChart license agreement covers the creation of chart types exposed via the Application Builder wizards, and an "Area" chart is not one of them. In order to generate chart types that are not covered by our license, you will need to approach AnyChart (anychart.com) yourself and obtain a separate license for generating such a chart type. While you may have been able to generate such an unlicensed chart type via custom XML in APEX 4.0.1, this will not be feasible in newer releases of APEX. So my recommendation would be to change your chart to replace the use of the "Area" series with a licensed series type e.g. Bar.