Are you using the same versions of dependencies in both projects?

i think i have found the answer.. and it might be a copy/paste or an old example that i have manually updated issue

looks like the issue was that i was missing the container - and i was plumbing in the PrimaryBlobConnectionString from the acocunt int to the container name. this brings an interesting point to the fore, one that i was suprised to see when you first presented it to me in Brighton, c# is a strongly typed language so really i shouldn't pass in a container name which is just a string, i should pass in the container object, which can be used to extract whatever is necessary.

i also had a case issue with the container... it created it fine with mixed case, but could then upload a file to it. second time of running it succeeded presumably because the container existed then, and azure had lower cased it. it is a small thing but it should really blow up.. or slightly more dangerously.. to lower everything.