Could not load type '****' from assembly'****, Version = 0.0.0.0, Culture=neutral, PublicKeyToken=null'

I was on a maintainence call this morning, and there was a minor problem to a certain page. I wont run into what the problem was, as it is out of context. After I was done with the bug, I swiftly published the project, and uploaded the project on to the live server. because I did not make any drastic changes to the project, out of habit, I just rolled the web.config file to the original settings, as to prevent typing the connection string for the database back again.

I made sure everything was working and in place and uploaded the project on to the live server! Bingo! Everthing was fine on the site and even for extended site testing on the links and database connection, it worked fine. The bug was resolved, and time to hit the next job!

Then towards the end of the day, I received a couple of mails regarding the web-parts section of the page is bugging up! I clicked the link on that page and it gave me this error:

Could not load type '****' from assembly'****, Version = 0.0.0.0, Culture=neutral, PublicKeyToken=null'

I could not figure out what exactly the problem was as, the version on the development server was still working smoothly. There was no other problem to the site, apart from web-parts. so what went wrong?

I tried to hit Google for the same topic, but to my amazement, there were many people out there who faced the same problem many a times, there was not a single solution, that explained the cause of the error. The closest I got was at www.dotnet247.com where the author said that there was some issue with app.config file, which he tried to reuse in another project. But I am not trying to reuse any file in a different project. It is necessarily the same project, with a couple of html and vbscript lines added to a page.

So in principle I am suppose to be able to update the project straight away! Me and my collegue, set on the journey to discover what is going wrong! I started doing all sort of permutations for the settings. After a while I had a thought, why not try to change the web.config file on the local copy and then publish the entire project to the live server, instead of replacing the web.config file!

I did that, and miracles do happen! The project started working at its best again. But the best thing was that instead of stopping after the problem was solved, I kept trying all the possible change, just to make sure, it was no fluke, and indeed it wasnt one.

So I figured out that even if there are minor changes to the site, do not recycle any files straight out of the pile. The second issue that has come to my mind now, is that if I can just change a single file from the published result! Will get back as soon as I have enough to write about that; till then happy programming!