Maybe a unnecessary question but:
The sitemap is showing fine when you try it in the browser?
And some general stuff:
Which OH Version, which Vscode version and which extension version are you using?
Also correct port? 
yup , standard 8080
yes browser worked, samba share working in windows 10
OH 2 latest download from yesterday , VSC OH 0.5.1
OK, i am out of simple solutions now, sorry. 
I will check the code for this and see if we can provide some useful logs for it.
ok, thx
Hey @wen62,
Could you try this extension please?
https://github.com/openhab/openhab-vscode/files/3775027/openhab-0.5.1_outputChannel.zip
It contains a new output Channel which should provide logging information.
(I have added this now as a general method, so we can extend user logging in the future easily.)
Should look like this:
Please note that this is just an experimental extension for digging into this problem.
Since it is packaged on my current codebase it may contain some flaws,
so you should switch to the released version, when we have finished testing.
I have actually the same problem. I am in the setup phase of my openHAB installation. Base is a Ubuntu Server 19.10 (minimal) with openHAB, Zulu and Samba. Installed with the official steps from the openHAV documentation. My Visual Studio Code runs in macOS 10.14.6 and in a virtual Windows 10 machine in VMware Fusion. Both VSC have the problem to show the sitemap. But they show configuration error (like an wrong “,”) and also shows in autocompletion e.g. things. Only the part with the sitemap gives an empty output. Opening in the same in Safari on macOS or in Firefox in Windows shows the sitemap.
Hi @iLion and welcome @ openHAB community,
Maybe you could also install the testing extension from my last post and show us the logs output it produces when you try to open a sitemap in basicUI.
I installed on a second windows maschine a fresh Visual Studio Code and the manual downloaded extension from your link. I got no more output, except the following line, when I try to open the sitemap preview: [Error - 08:07:17] Connection to server is erroring. Shutting down server.
What you describe is the openHAB server output, of which I have no influence.
There is a yellow marked drop-down in my screenshot.
You can change the output Channel through this and there should be a Channel openHAB extension available.
Please check if it is as explained and if the extension channel produced some more logs.
Is working perfectly now , thx a million!!!
I see now, excuse the confusion. Now my output is the following:
openHAB vscode extension has been activated
URL that will be opened is: http://openhabeusername:openhabpassword@192.168.178.234:8080/basicui/app?sitemap=standard
Creating new preview panel.
Updating new preview panel now...
Attempting to open Sitemap "standard" in BasicUI.
URL that will be opened is: http://openhabeusername:openhabpassword@192.168.178.234:8080/basicui/app?sitemap=standard
Creating new preview panel.
Updating new preview panel now...
I changed my username in the logoutput to “openhabeusername” and the password to “openhabpassword”. I did not see anything inside Visual Studio Code. But when I copy the original shown url to my webbrowser, i can see the basic ui.
I have changed nothing in the functional code 
Anyways i am happy that extension is working now for you, even if i would have loved to identify the problem that has lead to it.
Hey @iLion, would be great if you could use code fences in the future.
An explanation of how to use them in this forum can be found here: How to use code fences
This helps bringing code and looks in a nice readable and sometimes even colourful presentation.
Thanks in advance.
OK, this sintence confuses me a bit now.
Which version did work for you in the browser:
This one with user credentials?
http://openhabeusername:openhabpassword@192.168.178.234:8080/basicui/app?sitemap=standard
Or this one without user credentials?
http://192.168.178.234:8080/basicui/app?sitemap=standard
Hi, both versions copied to Safari in macOS 10.14.6 works without an error message. So first I copy with username and password, but it makes no difference. I can see and use my sitemap in an external browser.
Ok then i have another question on top.
When you use the link with username and password included in browser,
is it then rewritten in the browser adress bar to the vesion without user credentials?
I have tried this here and when i put in
http://openhabeusername:openhabpassword@192.168.178.234:8080/basicui/app?sitemap=standard
(of course with my IP and sitemap name)
it opens the BasicUI in Browser and in my browser the URL is shown as:
http://192.168.178.234:8080/basicui/app?sitemap=standard
I have to check if the authentication settings have in impact while trying to open it in vscode.
Yes, the URL is rewritten after sending.
Ok i have debugged it down and found the problem:
[Embedded Page] Subresource requests whose URLs contain embedded credentials (e.g. `https://user:pass@host/`) are blocked. See https://www.chromestatus.com/feature/5669008342777856 for more details.
Inside vscode there is a chrome engine running for the webview, so its like a browser hidden in vscode to view the BasicUI.
But chrome doesn’t allow us to request BasicUI with user credentials, at least in the way we are currently showing the BasicUI.
I have no fast solution for this, sorry.
I have additionally added an issue for this in our bug tracker, since authentication is a common usecase and of course it is a good thing in general, so i won’t encourage anyone to leave it behind for usability in vscode.