Problem: I want to show custom error messages on the community site for different http errors. 

I have visited the help page for Site Error Page (https://help.salesforce.com/articleView?id=sf.sites_error_pages.htm&type=5)but that wasn't helpful to me. The navigation page mentioned in help doesn't take me to the Community Site 'From Setup, enter Sites in the Quick Find box, then select Sites.' .... 

Instead I have to do 'All Sites > Select Workspaces > Administration > Pages > click Go to Force.com' which takes me to the same page given in help document. But assigning the error page doesn't show up on communities, whenever there is an issue it shows 'Invalid page' which is defined in Digital Experience Builder. 

Now if my understanding is correct I need to customize the pre-defined 'Error' page on Cummunity Experience Builder such that it recognize the http error type and show appropriate message. Please help how to achieve that?
 

Hey community,

I'm struggling with the logic of the task...

To complete this challenge, add a validation rule 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).Name the validation rule 'Contact must be in Account ZIP Code'.

A contact with a MailingPostalCode that has an account and does not match the associated Account ShippingPostalCode should return with a validation error and not be inserted.

The validation rule should ONLY apply to contact records with an associated account. Contact records with no associated parent account can be added with any MailingPostalCode value. (Hint: you can use the ISBLANK function for this check)

Here is what I got so far:

AND(
 NOT(ISBLANK(MailingPostalCode)),
 MailingPostalCode  <>  Account.ShippingPostalCode )

I THINK I know how to see if the contact mailing zip is not the same as the account shipping zip, and only if the is not blank.

The part I am stuck on is if the "Contact records with no associated parent account can be added with any MaiilingPostalCode value"...

I don't know what to do with that.

Also, I am now getting the error message when I recheck challenge:

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, Contact_must_be_in_Account_ZIP_Code: [] 

Double help, please.