Solution: After a bit of investigation, I found that the error was happening because the method call from SQL Server was attempting to use the HttpProxy on the Server machine. If the proxy is not set to null explicitly in your code, then you will get this error.

So to fix it, set the Proxy of the request object to null as follows (see line # 3) .
C# Version

FtpWebRequest request =
(FtpWebRequest)WebRequest.Create((string)ftpServerAndFolder + "/" + (string)uploadFileName);
// set proxy to null to avoid the System.InvalidOperationException: The requested FTP command is not supported when using HTTP proxy.
request.Proxy = null;
request.Method = WebRequestMethods.Ftp.UploadFile;
request.Credentials = new NetworkCredential((string)ftpUser, (string)ftpPassword);

VB.Net Version

FtpWebRequest request =
CType(WebRequest.Create(CType(ftpServerAndFolder + "/" + CType(uploadFileName, string, String))), FtpWebRequest)
' set proxy to null to avoid the System.InvalidOperationException: The requested FTP command is not supported when using HTTP proxy.
request.Proxy = Nothing
request.Method = WebRequestMethods.Ftp.UploadFile
request.Credentials = New NetworkCredential(CType(ftpUser, CType(ftpPassword, string, String)))

Restore the Security Tab for your Folders

• Right click Start and Click Explore to open a file explorer window.
• Click Tools > Folder Options. Click the View tab.
• In the View tab, scroll to the bottom until you see the “Use Simple File Sharing (Recommended)” checkbox.

  

• Uncheck the “Use Simple File Sharing (Recommended)” checkbox and click Ok.
• Now, right click any folder and click Sharing and Security…

  

• You should see the Security tab which will allow you to set user specific folder permissions.

“The database principal owns a schema in the database, and cannot be dropped. (Microsoft SQL Server, Error: 15138)”

The reason for this is that in SQL Server 2005, if a user is associated with a Schema, then that user has to be first replaced by another user in the schema before you can drop the user from the database.

Fix the Error

In SQL Server 2005 Management Studio, expand the node

Database > yourdatabasename > Security and then click Schemas. On the right pane, you will see a name value pairs list of the schemas and the corresponding owners.

For one or more of the schemas, you should see the user you are trying to drop listed as the owner. For each of these schemas, do the following.

• Right click the schema, and click Properties. In the schema owner box, type the name of the schema, ex. in the following, I would type db_admin over the mynewcommunity_admin.
• Click OK.
• After you do this for all schemas that the user you are trying to drop is the owner of, you should see something like this.

• Now, if you right click the user and click Delete, you should be able to successfully drop the user from the database.

Fix the ‘XML Parsing Error’

Click Start > Run, and type the following command depending on which ASP.NET framework is in use by the default web site in your IIS.

ASP.NET 2.0 Framework

%Windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -i

ASP.NET 1.1 Framework

%Windir%\Microsoft.NET\Framework\v1.1.4322\aspnet_regiis.exe -i

You should see a command window that is displayed briefly, that shows that ASP.NET is being installed. After the registration is successful, the window will be closed.

Now refresh the .aspx page that you got the XML Parser error for in the browser and your page should be rendered correctly.

Why did you get this error ?

I have seen this error happen to me in situations where I had installed IIS after the installing the .Net Framework. This make sense. If you install IIS after you install the .Net Framework, then the framework is not registered with IIS. So when a request for a .aspx page comes to IIS, it simply passes on the contents of the page as-is without processing it. So in effect, the browser receives the entire .aspx page’s code, tried to parse it as an XML file, encounters the parsing error at the second character in the page directive and stops.

Related: ASP.NET IIS Registration Tool

Allegedly Microsoft introduced this check in ASP.NET 1.1 to prevent scripting attacks. So how do you fix this ?

Fix the ‘A potentially dangerous Request.Form value was detected…’ Error

• Open the .aspx page in a text editor or in Visual Studio 2003.
• In the Page directive, add the following

• Save and close the .aspx file. This should fix it.
• This fix is only for that individual page. If you wanted to make this default for all your pages, then add the following in your <system.web> section of your web.config file.

Related : Caveats and Consequences of  validateRequest