puppet upgrade problem 0.25 "could not convert from pson"

By thomas, 20 November, 2009
After upgrading to 0.25, the following error occurs:
Could not retrieve catalog from remote server: Could not intern from pson: Could not convert from pson: Could not find relationship target ''
This turned out to be because of recipes using exec without naming the exec. Example
exec { "cat /that/file": unless => "something", path => "/bin", refreshonly => false }
should be rewritten as
exec { "cat that file": command => "cat /that/file", unless => "something", path => "/bin", refreshonly => false }
The error goes away after making the change and all is well.