Couple of tips when you're updating Mango Blog and you're running into vague "Couldn't upgrade database" messages with no further information.

Tip #1: Make sure your db user has the appropriate permissions (insert, update, select, delete, create, alter, drop).

Tip #2: Make sure that the DSN that is logging in as that db user has the appropriate permission:

Tip #3: After you're done updating, remember to remove Alter, Drop, Create.

Mango Blog 1.4 was released today. I went to upgrade, but I bumped into an issue and I wasn't able to track down what was failing. I stumbled around on the Mango forums until I came across this post that pretty much matches what I was having issues with.

Laura posted a response:

Open file components/Updater.cfc and change line 436 from:
<cfhttp url="#arguments.zipAddress#" method="get" path="#tempdir#">
to:
<cfhttp url="#arguments.zipAddress#" method="get" path="#tempdir#" file="#filename#">

This immediately fixed the issue and I've also written up a Railo JIRA ticket so someone can figure out what's happening with CFHTTP.