Unable to create backup to remote FTP storage:
Error: Unable to export backup: Transport error: Unable to create the directory 'ftp://192.0.2.2/backup/': Curl error: (21) Quote command returned error: Last FTP request: MKD backup Last FTP response: 550 backup: File exists
#PPPM-12798 "When Plesk fails to make a backup to an FTP storage, the correct error is now reported instead of “Error: Unable to export backup: Transport error: Unable to create the directory”."
- Plesk Obsidian 30 August 2021
If update is not possible for some reason you may try the following