When WHM refuses to create an account with "Account creation failed: quota exceeded" the message is unhelpful because there are three different "quotas" it could be talking about. This is the order to check them.
1. License account count
WHM Home → Server Status → Server Information shows the current account count and your license ceiling. If you're at the ceiling, this is your problem.
Fix: upgrade your license tier from your Panellicense dashboard. The new account limit applies within 5 minutes.
2. Filesystem quota
cPanel relies on Linux's per-user disk quota. If quotas are disabled or the quota database is corrupt, account creation fails with the same message.
# Check if quotas are enabled
quotacheck -av
# Force a rebuild
/scripts/fixquotas
3. Package quota
The package you're assigning to the new account may have a disk-quota field set higher than the free space on the partition. WHM checks before creating.
WHM Home → Packages → Edit a Package → check the Disk Quota (MB) field.
Decision tree
Account count at license ceiling?
├─ Yes → upgrade license
└─ No → run /scripts/fixquotas
├─ Errors → quota database corrupt, rebuild
└─ Clean → check the package's disk quota