Why I am unable to open the .xlsx files generated from Mendix?

Hi All, I am using Java actions to export the data to excel files. Here I am using .xlsx as file extension for the file name. When I try to open the generated file, I am getting the below error. The other files (which are not generated from Mendix) with .xlsx extension is opening. Also, when I change the file extension to '.xls’, it is working. But I want that file in '.xlsx’ extension only. Please help me with this error. Thanks in advance.   - Venkat
1 answers

XLS and XSLX are basicaly two different file formats, so changing the extension won’t change the format.
Which library are you using to generate the excel files? Maybe there is an option to configure the output format?
Alternatively, you can create an additional java action which converts XLS to XLSX using apache poi.