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IIS - Multiple web requests causing errors


We are using of Aspose.Cells. We have a full license for Aspose.Total .Net activated on our web server. When we make a single request everything works ok. But we when try to do 25+ concurrent requests we hit the following issue.

Unexpected exception: Aspose.Cells.CellsException: You are using an evaluation copy and have opened files exceeding limitation.
at .œ.()
at ”.ˆ.ž—(€ )
at ”.ˆ.Read(€ )
at ”.‡.()
at ”.‡.Read()
at ”.†.(Workbook , LoadOptions )
at Aspose.Cells.Workbook.Ÿ(Stream , LoadOptions , Boolean )
at Aspose.Cells.Workbook…ctor(Stream stream)

Any ideas why this may occur?




Thanks for providing us some details.

I guess your licensing code is not processed properly so the API will be used in evaluation mode. Kindly make sure that your licensing code should be processed first before using any other Aspose.Cells APIs in your code. Please see the document for your reference:

Generally, the license should be set on the beginning of the code, before any other functionality of Aspose.Cells is used. The license should be set only once, and it will remain licensed until the application is closed. In case of ASP.NET (IIS based) web application, good place to set license is Application_Start method. On this way you are sure that the license is set when application is started, and the license is set again if application is recycled for any reason.

One possible reason for the issue could be if you use the product after the web application is recycled and before the license is set again.

Let us know if you still have the issue.


We set the license on each web api call, Application_Start and Startup.Configuration:

<Assembly: OwinStartupAttribute(GetType(Startup))>
Public Class Startup
Public Sub Configuration(app As IAppBuilder)

End Sub

and with no luck.

If I were to make a single call to the web api after receiving this error the excel work would come back fine, without an evaluation details in the workbook.

Any other thoughts on what this could be caused by?

Thanks for the quick reply!



There is no need to set the license multiple times, you should only set it in Application_Start event. So, make sure to set the license properly in the event. Also, you may evaluate (at any place) if the license is set or not, see the document for your reference:

Moreover, please use fully qualified name when declaring objects just to make sure you are using right APIs, see the sample line of code:
Sample code:

Aspose.Cells.License lic = new Aspose.Cells.License();

If you still find the issue, kindly do create a separate web application (runnable), zip the project and post us here with all the files, we will check it soon. Also, give us details on how to reproduce the issue on our end.


Sorry, we narrowed down the cause of the issue.

The license was not being set in another service using web api.

Sorry for providing incorrect information. Thank you for your responses and time.



It is good to know that you were able to sort out this issue. Let us know if you encounter any other issue, we will be glad to look into it and help you further.