The alias name contains the character '&1', which is not permitted

What causes this issue?

To ensure the uniqueness of the alias name, it is compiled as follows:
<Package name>/<actual alias name>.
The character "/" can only appear as a separator between the package
name and the actual alias name.

How to fix this error?

Change the alias name.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.