Same build doesn't work on 2 different equal environments

I'm running out of options as to what this could be, hence my question here. I have a big dashboard type website at my company.

• The build is deployed to a Dev environment and a Production environment


• The 2 environments are equal in OS and Patch level.


• The entire code base deployed to both servers are 100% alike (as this is deployed through TeamCity and builds are promoted from dev to prod.)


• Ive changed web.config on prod to use the same connectionStrings (so DB issues could be ruled out)


• The ApplicationPools are also 100% equal - .NET 4 - integrated

The part that is failing is a model which gets its data from an SQL table, but apparently returns null (on the production environment, NOT on the dev environment)

It is only 1 view with a certain model that is failing with a null reference exception, and only on the production server, everything else works fine, all connections are fine - nothing .

An earlier build on the Production Servers works just fine (no errors) - and nothing has been changed to the site where the error resides.

Anyone with any good ideas?

I have a hard time believing this could be coding issues. But in my opinion, developers are the ones with the most experience with this sort of thing, hence me posting this question here.

I cannot, for the life of me figure out what could be left for me to try.

NB: I will not be posting code, as the code works in dev and locally and the older code base without changes to a few other views.