I have been using CorelDRAW X4 during some years. But only first time I saw Error reading a Corel3.cdr file. I've no idea what to undertake. I cannot continue my work in editor. I only wait someone or something that could aid me to solve it.
Try the following to repair corel draw file or you may learn some sources in the following
https://support.corel.com/hc/en-us/articles/216435167-How-To-Recover-Corrupted-CDR-Files
https://support.corel.com/hc/en-us/articles/216435747-Backup-and-Recovery-in-CorelDRAW-X6
https://coreldraw.recoverytoolbox.com/
- rename the file to ".zip "
- open the zip-file with Winzip or WinRar (these programs has a repair-function for zip)
- try to repair the file
- then extract the riffdata.cdr from content-folder of zip-file and open this file in CorelDRAW
These steps work for me.