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Convert PPTX to PDF - Charts are not rendered consistently

We are converting PPTX files to PDF's in a Windows Service. On some of our servers we have the problem that all charts are rendered skewed (correct width, too large height).
When I first saw this issue on a Windows 2008 R2 server, it vanished after I restarted the server. However now, after running ok for one month, it also happens on two of our Windows 2003 servers. In this case however the server reboot didn't solve the issue.

I now did some further testing using a simple command line application for the conversion from PPTX to PDF which I then call using a scheduled task. If I run the scheduled task while I'm logged in the chart looks ok. If however I schedule the execution and log out of the system the chart is skewed. I therefore conclude that the problem only happens if the app cannot "Interact with desktop". The issue however definitely doesn't happen consistently because the conversion is currently ok on two of our servers and not ok on two other servers.

Can you perhaps give me some background information on how the charts are converted to pdf? Are they using some OS functions that may or may not be locked? Hope you can give some insight. Thanks in advance.

- The source code of the command line testing app using the lasted Aspose.Slides.dll (Version
- Test.pptx (the source pptx which I used for testing the conversion)
- Converted_ScheduledTask_LogedIn.pdf (the pdf generated on the server while being logged in)
- Converted_ScheduledTask_LogedOut.pdf (the pdf generated on the server using the scheduled task and logging out of the system before the execution)v

Hi Martin,

Thank you for the details.

I have checked your issue on my Windows 8 x64 environment and I am unable to reproduce the issue with the latest version of Aspose.Slides for .NET. I will further test the issue on Windows Server 2008 R2 and will share the results with you soon.

Thanks & Regards,

Thanks for checking.

I just noticed that also the font size changes within the charts as you can see in the pdf's that I attached in the original post. If I generate the pdf while being logged in the font size is consistently 1.5 px smaller then when I generate the pdf while logged out. This effect seems to be more reliably reproduceable. Not sure if the two are related but perhaps this helps in the investigation.

Hi Martin,

Thank you for the details.

I am testing your issue and will get back to you with the results soon.

Thanks & Regards,

Can you give us some feedback on this?

It would be really interesting for me to know how technically the charts are converted from pptx to pdf even if you cannot provide a solution. If there is any dependency on OS tasks this information would help me because with that information I could ensure that that task is not busy during conversion.

I will soon have to make a call if we have to switch back to using Office on our servers for the conversions. I really dont want to go that route.


Hi Lukas,

Thank you for being patient.

Please see the attached files I generated on Windows Server 2008 R2 by creating a scheduled task which executed while I was logged in and later when I logged out. I don’t see any issue or different in result in both the cases.

I will further discuss with the development team regarding the any dependency on the OS while converting PPTX to PDF. I will update you regarding the discussion via this forum thread.

Thanks & Regards,

Have you been able to ask the dev teams if they have some ideas?

Hi Martin,

I have already created an investigation issue in our issue tracking system with id: SLIDESNET-35964 for our development team to further look into your issue and share the details regarding any dependency of the OS which is causing the problem at your end. As soon as a feedback is shared, I will update you via this forum thread.

Thanks & Regards,