I get that error in the title when saving the excel file to pdf. This is in Android by the way. My code is basically like this:
Workbook workbook = new Workbook(filePath);
workbook.save(“MyPdf.pdf”, SaveFormat.PDF);
The filePath is a string that has a value of the file path of the excel file. I already granted those permissions in the manifest like what others would suggest yet I still have this error. With or without that ".pdf" extension, it will still not work.