SharePoint 2010 URL limits not completely understood

Question

My team and I are trying to test the limits of SharePoint 2010 - specifically around URL and path lengths. In our root web, we created doc library that contains a main folder with an arbitrarily long name that includes spaces, similar to what we'd expect a user to potentially do.

When we upload files to the library/main folder some files are accepted without issue and others warn that they surpass the URL limit in SharePoint and have to be opened from the local desktop. The problem is that the URL in either case is 400+ characters and hence I would assume we wouldn't be able to add any documents based on Microsoft's URL Path Restrictions for SP 2010.

Why am I am able to upload documents with URL's greater than 256? Why can I upload some and not others? What are the true rules for path/url lengths in a scenario like this?

Answer 1

For each special character, that character length is multiplied by three. I.E. '@' now turns into 3 characters into the URL. Count the number of special characters for the file that got uploaded with the file that didn't.

Also the paths get stored in different areas:

Excerpt:

The limitations In this section apply to the total length of the URL path to a folder or a file in SharePoint Foundation 2010 but not to the length of any parameters. Also, these limitations apply only to un-encoded URLs, not to encoded URLs. There is no limit to encoded URLs in SharePoint Foundation 2010. The limitations are the following:

• 260 Unicode (UTF-16) code units – the characters in a full file path, not including a domain/server name.

• 256 Unicode (UTF-16) code units – the characters in a full folder path, not including the file name and the domain/server name.

• 128 Unicode (UTF-16) code units - characters in a path component, that is, a file or folder name.

• 260 Unicode (UTF-16) code units – the characters in a full path, including a domain/server name for use with Office clients.

• 256 Unicode (UTF-16) code units – the characters in a full path including the domain/server name, for use with Active X controls.

Maybe there are characters that you are including that do not fall in these unicodes.

Here is more on the URL limitations:

http://technet.microsoft.com/en-us/library/ff919562(v=office.14).aspx