Comments on: ASP.NET 400 Bad Request with restricted characters

By: Tom Scarr

Tom Scarr — Wed, 02 Jun 2010 10:06:13 +0000

I’m having a similar issue with the ‘ASP.Net 400 Bad request with restricted characters’ issue when hosting with IIS7. I am base 64 encoding some of the parameters. I cannot see any problematic characters such as ampersands etc in the following url:

http://localhost/Revolution/PrintingWm/PrintPageAsPdf/1/UGVyZm9ybWFuY2UgT3ZlcnZpZXcgLSA1WSBFcXVpdHk/eyJhbmFseXNpc0V4ZWN1dGlvbklkIjoic2hhcnJpczsyODNkZjQxOC03MDgxLTQ2MWQtODEwYi1lMzU1ZTYzNjk4NGEiLCJwZXJpb2RDb2RlIjoiRWFybGllc3QiLCJzdGF0aXN0aWNzTWVhc3VyZUxheW91dElkIjoiMzIiLCJiYXJDaGFydE1lYXN1cmVMYXlvdXRJZCI6IjYwIiwibnVtYmVyT2ZMb3dWYWx1ZXMiOjUsIm51bWJlck9mSGlnaFZhbHVlcyI6NX0=

Can anyone suggest whether there are problematic characters here that would cause ASP.Net to be unhappy? I may end up resorting to query strings as that seems to work. But I’m still confused as to why this Url would not be accepted.

By: Vijay Santhanam

Vijay Santhanam — Wed, 27 May 2009 05:55:29 +0000

This feature is rather annoying. Wish there was more info about this issue by MS. Explaining why, and maybe a turn off feature if need be.

Also, a replacement string formatter would be nice

By: Joshua Flanagan

Joshua Flanagan — Fri, 15 May 2009 13:40:41 +0000

First, whether its a bug or not doesn’t really matter to me. I’m merely providing info on 2 different ways to deal with it (by changing the framework behavior, or working around it).
Second, its hard to call it a bug with MVC, since none of the MVC code is causing the problem – its in the underlying ASP.NET layer.
Third, I think I’d classify it as “default behavior that you disagree with”. The framework was designed to operate in 2 modes “allow those characters in the path”, or “dont allow those characters in the path”, with documented ways to change the mode. They chose “dont allow” as the default mode, but you can change it if you disagree (by following the KB articles linked in the Dirk.Net post mentioned above).
Fourth, yes its really annoying!

By: Ben

Ben — Fri, 15 May 2009 12:03:29 +0000

Totally agree with benb’s assesment.

We use custom URL rewriting in asp.net 2.0 (not MVC routing) precisely so we don’t have to use ugly URLs like :

http://localhost/dovetailcrm/contacts/query?search=%25%20%25

This is a bug. For us a really really annoying one.

By: benb

benb — Tue, 28 Apr 2009 17:49:31 +0000

to me this is a bug. It is one I submitted last year for MVC and never has been resolved. The problem is, when one is trying to make a RESTful service (as an example), ALL valid characters as defined by the standard should be acceptable.

What I found is, basically any character that is not valid for a Windows file name causes this issue. With routing, this is a bug. Given we are not looking for a specific disk file, all protocol standard characters should be considered valid. When looking at something like the Yahoo! Boss API, with MVC or anything on ASP .NET, you would not be able to pass in the query in the same way? Why? This is not correct as it does not work the way it should and the way the standards say it should.