Sorry to hear the inconvenience caused.
What happens when you are trying to convert the pdf file? Is it giving any specific error while converting the document?
If you are trying the conversion online, then you may try with a different web browser https://cloud.acrobat.com/exportpdf
or check with a different file.
Or use the desktop application Adobe Reader DC - Adobe Acrobat Reader DC Install for all versions
For more details you may see-
Sorry for the delay in response and for the inconvenience caused to you.
This issue is not reproducible in-house neither we find any issue with the service at all. Would you kind to let us know if this issue is still happening at your end or it is fixed.
If you were able to fix it, would you please help us with your findings?
Will be waiting for your response.