The site never had any issues with adding these until recently, but now whenever I try to add any I get: "Cannot insert the value NULL into column 'sortOrder', table 'dbname.dbo.umbracoDomain'; column does not allow nulls. INSERT fails." This is with adding the current domain, then any sub paths or even a new domain. I'm trying to understand what could be causing this issue to pop up as I have never seen it before.

Hi @Jordan.Smith did you perhaps upgrade your umbraco nuget packages ? Because this column has been added in Umbraco 11.3 : https://github.com/umbraco/Umbraco-CMS/blob/v13/contrib/src/Umbraco.Infrastructure/Migrations/Upgrade/V_11_3_0/AddDomainSortOrder.cs

Not from what I recall, I will need to check, as this issue suddenly started popping up after I returned from my holiday. So I am not sure if one of the teams done something that I am not aware of or not, I havent saw anything yet that would suggest a change. We are on 10.8.6 right now if I am correct.

maybe another dependency pulls in a newer nuget version of Umbraco