when trying to deploy a OVA template I made to migrate some server. I got this weird error.
Deploy OVF template
The task 
canceled by 
a user.
Really, I didn't do anything.

How to Fix
with 7zip, unzip your OVA template
delete the file .mf file
edit the .ofv file and change
Changing the above line, to read…
then save.
To deploy;
Deploy OVA file from File menu.
Select the folder you unzipped
Select the ovf file.
worked for me.
This was on ESXi, 5.1.0