Access Denied even to SharePoint Administrator

Message
Access Denied.
Editing/Settings are NOT enabled even for administrators.

Context
SharePoint Site Collection, maybe after backup/restore a site collection

Explanation
The Site Collection is in "Read only" mode. Maybe due to a stsadm backup brutally interrupted.

Solution
Open the SharePoint Central Administration. Under Application Magement, click on the "Configure quotas and locks" link. Than have a look under the section "Site Lock Information" and be sure it is selected "Not locked" option.

UnauthorizedAccessException opening UNC path file with FileStream

Message

UnauthorizedAccessException: Access to the path '...' is denied.

Context
Executing the following line of code (C# ASP.NET under Visual Studio, localFile or UNC path)

FileStream fs = new FileStream(fileName, FileMode.Open);

Explanation
ND

Solution
Add the fileaccess mode option "FileAccess.Read":
FileStream fs = new FileStream(fileName, FileMode.Open, FileAccess.Read);