Hosting is

MSSQL 2014 ASP.Net 4.8.3761 iiS10

File permissions are all set to read write create (Full Control)

This meets all the umbraco criteria

Put a none uskinned umbraco 8 site up and works fine.

Thanks Marc

That go that solved for others the next lines that are going to cause an issue is in USNExamineEvents.cs

I solved it like this (Marc please correct if I havent interpreted it correctly)

_examineManager = examineManager ?? throw new ArgumentNullException(nameof(examineManager));
_umbracoContextFactory = umbracoContextFactory ?? new ArgumentNullException(nameof(umbracoContextFactory));

I changed these to

try
            {
                if (examineManager.GetType() != null)
                {
                    _examineManager = examineManager;
                }
            }
            catch { }

and

        try
        {
            if (umbracoContextFactory.GetType() != null)
            {
                _umbracoContextFactory = umbracoContextFactory;
            }
        }
        catch { }

However I are having a little more difficulty with

if (!_examineManager.TryGetIndex("ExternalIndex", out IIndex index))
                throw new InvalidOperationException("No index found by name ExternalIndex");

so far I have come up with

try
            {
                if (!_examineManager.TryGetIndex("ExternalIndex", out IIndex index))
                {
                    //we need to cast because BaseIndexProvider contains the TransformingIndexValues event
                    try
                    {
                        if (!(index.GetType() == typeof(BaseIndexProvider)))
                        {
                            BaseIndexProvider indexProvider = (BaseIndexProvider)index;
                            indexProvider.TransformingIndexValues += IndexProviderTransformingIndexValues;
                        }
                    }
                    catch
                    {
                        new InvalidOperationException("Could not cast");
                    }
                }                
            }
            catch
            {
                new InvalidOperationException("No index found by name ExternalIndex");
            }

but cant find a way round the "out"

Thanks again marc

for those that come accross this the code now looks like

try
            {
                IIndex index = null;
                if (!_examineManager.TryGetIndex("ExternalIndex", out index))
                {
                    //we need to cast because BaseIndexProvider contains the TransformingIndexValues event
                    try
                    {
                        if (!(index.GetType() == typeof(BaseIndexProvider)))
                        {
                            BaseIndexProvider indexProvider = (BaseIndexProvider)index;
                            indexProvider.TransformingIndexValues += IndexProviderTransformingIndexValues;
                        }
                    }
                    catch
                    {
                        new InvalidOperationException("Could not cast");
                    }
                }                
            }
            catch
            {
                new InvalidOperationException("No index found by name ExternalIndex");
            }

The next question is

Usnstyle websiteStyle = (Usnstyle)Model.WebsiteStyle;

CS0246: The type or namespace name 'Usnstyle' could not be found (are you missing a using directive or an assembly reference?)