Sorry to hear about the trouble.
Is this error message coming up with all the pdf conversion or only this specific file? Have you checked with a different file?
If not, then you may try the following troubleshooting steps to see if that makes a difference-
1- If working on desktop application, then check is you are able to complete the conversion online, via- https://cloud.acrobat.com/exportpdf
2- If it works online, then you may check the desktop application's update. Open Adobe Reader>Help>Check for Update and try again.
4- If there is any internet security software, then please turn it off for a while and try exporting the file.
[Antivirus software can help protect your computer against viruses and other security threats. In most cases, you shouldn't disable your antivirus software. If you have to temporarily disable it to install or activate other software, you should re-enable it as soon as you're done.]