I found several service requests that our customers are trying to proceed with a backup of a Azure SQL Managed Instance to Azure Storage Account and they are facing an error, after reaching 40%: Backup failed for Server "servername". Failed: 1117 (The request could not be performed because of an I/O device error).
Working on this issue I found:
I found that the size of the database is +/- 300 GB.
The error message reported an I/O device error but not that the Azure Storage Account space is full.