I have followed the setup instructions and it says that the install will pick up the fact that its an empty db and install the data structures?

An unhandled exception occurred while processing the request.

SqlException: Invalid object name 'yaf_User'.

Any pointers appreciated as I want to prototype this Forum with the view of eventually integrating it into an existing ASP.net site.

I assume you run the solution in debug mode. By default visual studio halts on every try/catch block. The error you are getting is handled in the catch block. 

You can click on continue debugging in vs or change the default behavior vor the yaf dlls.

If I create a YAF_User table with a basic id/name column - it then errors again but lists out the expected columns.

Like this:

An unhandled exception occurred while processing the request.

SqlException: Invalid column name 'BoardID'.

Invalid column name 'Flags'.

Invalid column name 'BoardID'.

Invalid column name 'ProviderUserKey'.

Invalid column name 'Name'.

Invalid column name 'DisplayName'.

Invalid column name 'Joined'.

Invalid column name 'LastVisit'.

Invalid column name 'IP'.

Invalid column name 'NumPosts'.

Invalid column name 'TimeZone'.

Invalid column name 'Avatar'.

Invalid column name 'Signature'.

Invalid column name 'AvatarImage'.

Invalid column name 'AvatarImageType'.

Invalid column name 'RankID'.

Invalid column name 'Suspended'.

Invalid column name 'LanguageFile'.

Invalid column name 'ThemeFile'.

Invalid column name 'AutoWatchTopics'.

Invalid column name 'DailyDigest'.

Invalid column name 'Activity'.

Invalid column name 'NotificationType'.

Invalid column name 'Flags'.

Invalid column name 'BlockFlags'.

Invalid column name 'Points'.

Invalid column name 'Culture'.

Invalid column name 'UserStyle'.

Invalid column name 'SuspendedReason'.

Invalid column name 'SuspendedBy'.

Invalid column name 'PageSize'.

Invalid column name 'DarkMode'.

Microsoft.Data.SqlClient.SqlConnection.OnError(SqlException exception, bool breakConnection, Action wrapCloseInAction)

Stack 

Query 

Cookies 

Headers 

Routing

SqlException: Invalid column name 'BoardID'. Invalid column name 'Flags'. Invalid column name 'BoardID'. Invalid column name 'ProviderUserKey'. Invalid column name 'Name'. Invalid column name 'DisplayName'. Invalid column name 'Joined'. Invalid column name 'LastVisit'. Invalid column name 'IP'. Invalid column name 'NumPosts'. Invalid column name 'TimeZone'. Invalid column name 'Avatar'. Invalid column name 'Signature'. Invalid column name 'AvatarImage'. Invalid column name 'AvatarImageType'. Invalid column name 'RankID'. Invalid column name 'Suspended'. Invalid column name 'LanguageFile'. Invalid column name 'ThemeFile'. Invalid column name 'AutoWatchTopics'. Invalid column name 'DailyDigest'. Invalid column name 'Activity'. Invalid column name 'NotificationType'. Invalid column name 'Flags'. Invalid column name 'BlockFlags'. Invalid column name 'Points'. Invalid column name 'Culture'. Invalid column name 'UserStyle'. Invalid column name 'SuspendedReason'. Invalid column name 'SuspendedBy'. Invalid column name 'PageSize'. Invalid column name 'DarkMode'.

Help! - any ideas I really am pulling my hair out with this now.

The fix for the issue is already committed in the source repository.

An unhandled exception occurred while processing the request.

SqlException: Invalid object name 'yaf_User'.

Microsoft.Data.SqlClient.SqlConnection.OnError(SqlException exception, bool breakConnection, Action wrapCloseInAction)

Stack 

Query 

Cookies 

Headers 

Routing

SqlException: Invalid object name 'yaf_User'.

Microsoft.Data.SqlClient.SqlConnection.OnError(SqlException exception, bool breakConnection, Action wrapCloseInAction)

Microsoft.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, bool breakConnection, Action wrapCloseInAction)

I'll take the master and give it another try - Thanks

When I view the page source I can see the installer guide text - so its there but nothing displaying.

This is in the view source;

Welcome to the YAF.NET Installation

Click "Next" to start the Install process.

This Installer will guide you through the steps required to Install YetAnotherForum.NET (YAF.NET).

Next

Welcome to the YAF.NET Installation

Click "Next" to start the Install process.

This Installer will guide you through the steps required to Install YetAnotherForum.NET (YAF.NET).

Next

Are the installation instructions for v4 being updated?

I have put my db connection string in the aappsettings.json.

Yaf 4 has not been released yet and that's why there is no install guide yet.

But there is an building guide

https://github.com/YAFNET/YAFNET/wiki#building-the-source  

You need to compile the js and css separate.

I have tyried both versions listed in Downloads and have the same background screen with no instructions.

When you say compile .js and css seperately - I have run grunt.js

Severity    Code    Description    Project    File    Line    Suppression State

Error    MSB3073    The command "node_modules\.bin\grunt" exited with code 6.    YAF-SqlServer    C:\Users\phil_\source\repos\YAFNET\yafsrc\YetAnotherForum.NET\YAF-SqlServer.csproj    49    

Points at this in the csproj.cs

Possible solution runt 

npm install -g ruby sass

from the command in the YetAnotherForum.NET folder