Outlook Web Add-in MVC -> Call Controller in TaskPane - asp.net-mvc

Question

i am trying to develop an outlook web mvc addin with visual studio 2017.
I successfully integrated my XML-Manifest, the ribbon button is added correctly and the task pane opens after clicking my button.
Anyway my view cannot be displayed!
My error message is the same as "Shyam sundar shah" got more than a year ago:
"Add-in error: Something went wrond and we couldn´t start this add-in. Please try again later or contact your system administrator."
Outlook web addin is not loading in Outlook webApps using MVC
I linked the question cause i am not able to link any images in my questions yet.
Here is my Extensionpoint in the manifest:
<ExtensionPoint xsi:type="MessageReadCommandSurface">
<OfficeTab id="ReadTab">
<Group id="ReadGroup">
<Label resid="ReadGroupLabel" />
<Control xsi:type="Button" id="msgReadOpenPaneButton">
<Label resid="ReadButtonLabel" />
<Supertip>
<Title resid="ReadSuperTipTitle" />
<Description resid="ReadSuperTipDescription" />
</Supertip>
<Icon>
<bt:Image size="16" resid="icon" />
<bt:Image size="32" resid="icon" />
<bt:Image size="80" resid="icon" />
</Icon>
<Action xsi:type="ShowTaskpane">
<SourceLocation resid="ReadPane" />
</Action>
</Control>
<Control xsi:type="Button" id="msgReadOpenPaneButton2">
<Label resid="ReadButtonLabel2" />
<Supertip>
<Title resid="ReadSuperTipTitle2" />
<Description resid="ReadSuperTipDescription2" />
</Supertip>
<Icon>
<bt:Image size="16" resid="icon" />
<bt:Image size="32" resid="icon" />
<bt:Image size="80" resid="icon" />
</Icon>
<Action xsi:type="ShowTaskpane">
<SourceLocation resid="ReadPane2"/>
</Action>
</Control>
</Group>
</OfficeTab>
</ExtensionPoint>
<bt:Urls>
<bt:Url id="functionFile" DefaultValue="https://localhost:44302/Functions/FunctionFile.html"/>
<bt:Url id="ReadPane" DefaultValue="https://localhost:44302/Home/Login"/>
<bt:Url id="ReadPane2" DefaultValue="http://localhost:12543/Home/Login"/>
</bt:Urls>
As you can see i tried the SSL and the non SSL path. Both throw the same error.
My controller action is as simple as possible. I am just testing a local initialized variable of being true or false and in both cases i return the View with a correspondenting Model. So I dont think my problem is hiding there.(the cases will be completed later, cause there is no relation to my problem):
private bool _unconnect = false;
public ActionResult Login()
{
LoginModel model = new LoginModel();
if (!_unconnect)
{
return View(model);
}
else
{
return View(model);
}
}
I didn´t found any solution in the above linked question or anywhere else.
Are there any new cognitions for this error?
Thanks in advance.