The update process built into Alfred has failed for me in each of the last few releases. In each case I get a message like "Unable to verify v2.0.6 b203" after I try to update, and Alfred fails to update. Next time I start the computer I get asked to update again, and again it fails.
This has happened ever since I've installed Alfred — I think the first version I had was v2.0.2. I have to manually download each new version from your website, and copy it over the existing installation. In this example I am using v2.0.4, but it occurs for v2.0.5 as well as older versions.
It starts with the popup telling me there's an update available:
I click Update and the download starts:
The download appears to finish correctly, but then immediately afterwards the verification error is displayed:
I've looked at the network traffic, and it looks like the download works OK. In the above example, Alfred made two requests which both completed successfully:
That second request resolved to 18.104.22.168 (vip1.AU-anycast1.cachefly.net) which is an Australian cachefly server (I do live in Australia). Is it possible that the file is corrupted on this server and not others? Note however that I've had the same problem with previous releases so it can't be just the Alfred_2.0.6_203.zip file that is to blame.
Finally, I've checked the logs in Console.app and there's nothing relevant from Alfred there (just a single startup message after booting up).