hello, I used dotfuscator for my dlls and after publishing the website it seems that it can't find pages names. so do I have to use dotfuscator for web pages also? how to correct this error
You don't have to obfuscate a web site/application since you probably won't distribute the web site binaries publicly. Only the web server will have access to it and the bin folder is protected from web access so nobody will download your website's dll.
Why do you need to use obfuscation?Is it that you want to improve your performance of the application.If so then use gzip compression instead of obfuscation because obfuscation is not 100% safe.It might lead to unwanted errors.
gzip compression can decrease the number of bytes sent by your server. This cuts down on bandwidth usage. Depending on the data sent, how well it can be compressed, and whether the client browsers support it (IIS will only send gzip compressed content to clients that support gzip compression, such as Internet Explorer 6.0 and Firefox), your server can serve more requests per second. In fact, just about any time you can decrease the amount of data returned, you will increase requests per second.gzip compression is built into IIS 6.0 and is much better than the gzip compression used in IIS 5.0. Unfortunately, when attempting to turn on gzip compression in IIS 6.0
By default every method name and class in your input assembly is renamed but Dotfuscator (and other obfuscators) are not aware of what you are accessing via the .aspx pages (bound controls, etc.) so you need to be sure to exclude any items that your .aspx markup or embedded script are accessing either by name or reflection.
See this Knowledge Base article for a potential starting point.