As I told you that Circular references exception has many scenarios so we might not provide complete details. Anyways, we will still check if we could provide further details on the excretion.
For your information, Aspose.Cells is written in pure Java, so , concurrency and multithreading should not be a problem by any means. Our several users do use the component in their diverse environments in different types of (desktop, client server etc.) solutions or other scenarios without any problem. As long as you don’t have shared data source and every time a user access the application a new Workbook or Excel file is generated, there would be no problem at all. However, if you have a shared data/resource, then you will have to do synchronization by yourself. Also, in that case, we recommend you to create/manipulate of filling data into different workbooks in different threads accordingly, because, you should not use one workbook/file in multiple threads at the same time least you would not get stable data due to restrictions and complexity (involved) put forth by MS Excel file format(s) itself.