Help: I have created a Validation which will block the insertion of a contact if the contact is related to an account and has a mailing postal code (which has the API Name MailingPostalCode) different from the account's shipping postal code (which has the API Name ShippingPostalCode).
I tested the validation and I know it works because it gives the correct error message for this scenario however I am recieiving this error from Trail Head when I click on the green Check Challenge button :

There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Insert failed. First exception on row 0; first error: STORAGE_LIMIT_EXCEEDED, storage limit exceeded: []

2) I checked Data Management and I have a lot of space for creating a contact (1% or 99% free space)
For accounts I am at 93% full but I am not creating another account.

IS it the account percentage that needs reducing even though I am not creating another Account obejct at 93%?  Thanks for your help on this.