The Project Location is not Trusted

Dealing with the dreaded blocked files problem

Quickly Unblocking files marked as Unsafe

Ever download a Zip (or other files) and have to manually “Unblock” one or more files through Windows Explorer’s Properties dialog, like this?

Perhaps you been mystified by a message like this one from Visual Studio?

Mysterious Visual Studio error message

Read on to understand what’s happening and to learn how to more easily deal with Unblocking such downloaded files on Windows 7, Vista, and XP.

Why does this happen? Why do files become “Blocked”?

It appears that Internet Explorer (versions 7 and  8, maybe late patches in IE 6) applies the “block” in a stream (see below for more on streams). Some programs handle these “blocked” files more gracefully than others (looks like the latest Adobe PDF reader can read files like this w/o error).

I’ve seen blocking happen when downloading Visual Studio solutions from the web or from an email. I’ve also seen it when downloading documents to disk for use later. You can view the file’s properties in Windows Explorer to see if the block is there (look for the “Unblock” option, as seen above).

Another option is to use Notepad as illustrated in Colin Mackay’s Tip of the Day from nearly a year ago:

notepad MyDownloadedFile.zip:zone.identifier

Of course, substitute your filename in instead of BostonAzureSite.zip, but keep everything else identical. You will see the external zone stream:

[ZoneTransfer]
ZoneId=3

Windows is protecting us from ourselves. I guess if you don’t know what you are doing, you could hurt yourself; you’ve downloaded something “untrusted” from the interweb. This “protection” is in Windows 7 and Windows Vista, and apparently can even appear in Windows XP if certain Microsoft software updates are installed. I assume this has some benefits to someone!

But if you are a programmer / hacker / techie, and are comfortable hacking and generally know what you are doing, read on…

Easily Unblock downloaded files marked by IE as Unsafe

Normally, to Unblock files, you need to visit them one at a time with Windows Explorer, pop up the properties, and click on the Unblock button. This is tedious. If you want to be able to Unblock files more quickly, including whole directory trees at once, then consider doing the following.

Go get streams.exe from the big brains at Systinternals (which is part of Microsoft) and copy the executable to c:\bin\streams.exe. (If you put it somewhere else, make a compensating adjustment in the next step.)

Use Notepad to save the following into a text file named unblock-menu.reg and save it to disk:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\Directory\shell\UnBlock]

[HKEY_CLASSES_ROOT\Directory\shell\UnBlock\command]
@="c:\\bin\\streams.exe -d -s \"%1\""

[HKEY_CLASSES_ROOT\*\shell\UnBlock]

[HKEY_CLASSES_ROOT\*\shell\UnBlock\command]
@="c:\\bin\\streams.exe -d \"%1\""

What do these Registry Settings do?

This file lists some registry settings that will allow you to invoke streams.exe from the right-click context menu in Windows Explorer. Depending on whether you right-click on a folder or a file, the context menu will vary, as will the action. For a folder (directory), the registry setting says “call the program streams.exe with the parameters ‘-d -s’ and name-of-whatever-folder-i-clicked-on” which will cause streams.exe to visit each file in that directory tree and remove its streams information. If you right-click on just one file, the command is similar, except does not use the “-s” flag (which says to recurse into subdirectories).

Now install these registry settings by executing this file, probably by double-clicking on unblock-menu.reg from Windows Explorer. You will probably get a warning from Windows saying you must be nuts to attempt to modify the registry. However, if you are a programmer you are probably cool with it (and may also be nuts).

Now you are ready for the next time Windows protects you from yourself by blocking content you didn’t want marked as unsafe in the first place. You can right-click on any file or directory on your computer and select “Unblock” and that will apply the Unblock process. If you apply it to a file, it will only impact that file. If you apply it to a directory (aka folder) then it will recursively apply to all files and directories below that folder.

Here’s what you will see when you right-click on a directory / folder from Windows Explorer – note the new option:

And here’s what you will see when you right-click on a file:

Other Options

I learned about the streams.exe utility from a handy post about unblocking files for Vista. In that same post, they describe how to turn the feature off altogether using the Policy Editor.

Caveat Emptor

With great power comes great responsiblility.

I do not advise applying streams.exe to C:\ as I have no idea whether it is ever a good idea to remove all streams from all files. This may in fact be a very bad thing to do. I just don’t know.  I am personally comfortable doing it with Visual Studio projects and various documents I’ve downloaded, and have not run into any trouble, but be careful out there…

Note that the streams utility will nuke *all* the streams. So if your files contain useful additionals streams, this is probably not going to be a helpful strategy. I expect this is not likely to be a problem for the vast majority of people.

Interesting write-up on Alternate Data Streams, which are a feature of NTFS file system. Even some interesting streams hacks out there.