Runtime Error on Admin Page but other pages okay

Topics: Installing Orchard, Troubleshooting
Feb 21 at 7:03 PM
New installation of Orchard 1.10.1.0 on Windows Server 2016 , was working fine until I changed to a different theme and I'm now getting runtime error. I went back to the original theme (default Theme Machine) but error persists. Funny thing is, I can access the other page i.e. mysite/admin throws error but mysite/admin/themes works fine and aloows me to install different themes.

Here is the error detail- the error is on line 38:
Line 36:     <fieldset>
Line 37:         <select id="@Html.FieldIdFor(m => m.Swatch)" name="@Html.FieldNameFor(m => m.Swatch)">
Line 38:             <option value="bootstrap.min.css" @if (Model.Swatch.EndsWith("bootstrap.min.css")) { <text>selected="selected"</text> }>@T("Default")</option>
Line 39:             <option value="amelia.min.css" @if (Model.Swatch.EndsWith("amelia.min.css")) { <text>selected="selected"</text> }>@T("Amelia")</option>
Line 40:             <option value="cerulean.min.css" @if (Model.Swatch.EndsWith("cerulean.min.css")) { <text>selected="selected"</text> }>@T("Cerulean")</option>

Source File: e:\Me\Orchard\orchard\Themes\Bootstrap\Views\Admin\Index.cshtml    Line: 38 

Stack Trace: 

[NullReferenceException: Object reference not set to an instance of an object.]
   ASP._Page_Themes_Bootstrap_Views_admin_Index_cshtml.Execute() in e:\Me\Orchard\orchard\Themes\Bootstrap\Views\Admin\Index.cshtml:38