Not able to Visual Studio in Debug mode for a web page

Question

Just installed Visual Studio Community 2026.

Tried to run a simple "Hello World" web page and get the following:

Access is denied.

__Description:__An error occurred while accessing the resources required to serve this request. You might not have permission to view the requested resources. __Error message 401.3:__You do not have permission to view this directory or page using the credentials you supplied (access denied due to Access Control Lists). Ask the Web server's administrator to give you access to 'Z:\Code\WebApplication1\WebApplication1\WebForm1.aspx'.

---

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.8.9316.0

I did see a comment saying that the updated framework 4.8 was preventing debugging.

How can I get back to debugging my code?

Answer 1

Thank you for reaching out.
The error 401.3 – Access denied due to ACLs usually means the web server (IIS or IIS Express) doesn’t have permission to read your project files. It’s not caused by the .NET Framework version. Most often this occurs when the project is on a network or external drive (like Z:\) or when folder permissions block the account running the web server.

Workarounds:

1. Move the project to a local drive (e.g., C:\Projects). IIS Express often blocks network paths during debugging.
2. Check folder permissions – Make sure your user account (or IIS_IUSRS if using full IIS) has Read & Execute rights on the project folder.
3. Run Visual Studio as Administrator – This can bypass permission issues during debug.
4. Verify authentication settings – In Web.config, set authentication mode="None" or ensure the account is allowed if using Windows Authentication.

Quick fix: Moving the project to C:\ and running Visual Studio as Administrator solves most cases.

Please let us know if you require any further assistance, we’re happy to help.

If you found this information useful, kindly mark this as "Accept Answer".

Answer 2

You probably need to run vs as admin. Right click and select run as admin. I just make copy of the short cut and set run as admin in the shortcut. You can even drag the shortcut to the menu bar.