I am trying to solve this chalange:
Create an approval process that validates when a Prospect Account becomes a Customer.

I think I have done every steps correctly but still getting this error:

Challenge Not yet complete... here's what's wrong: 
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: FIELD_CUSTOM_VALIDATION_EXCEPTION, Value should be number: [SLASerialNumber__c]
I have tried this in 3 different developer page but still getting the same error

Challenge Not yet complete... here's what's wrong: 
An update to an account record failed to update the mailing address fields of all child contact records. Make sure that the process is correct and that it is activated.
Create a process to update child record when the parent is updated.
You've been given a requirement to keep Contact addresses in sync with the Account they belong to. Use Process Builder to create a new process that updates all child Contact addresses when the address of the Account record is updated. This process:
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Can have any name.
Must be activated.
Must update Contact mailing address fields (Street, City, State, Post Code, Country) when the parent Account shipping address field values are updated.
NOTE: You may have to deactivate the validation rule for the Contacts object (created from a previous challenge) in order to complete this challenge.
react-text: 37 /react-text
Check challenge

I am trying to solve this chalange:
Create an approval process that validates when a Prospect Account becomes a Customer.

I think I have done every steps correctly but still getting this error:

Challenge Not yet complete... here's what's wrong: 
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: FIELD_CUSTOM_VALIDATION_EXCEPTION, Value should be number: [SLASerialNumber__c]
I have tried this in 3 different developer page but still getting the same error