Conga Composer URLs are notoriously sensitive to copy paste errors where you inadvertently do things like this formatting structure:
in order to make the buttons readable in the SFDC point-and-click UI.
If you copy and paste from a detail page of a custom button, the copy paste operation will insert a non-visible space at the end of every line.
I always clicked Edit on a composer button and then did the copy before pasting into a second button's Edit window. This avoids the inadvertent trailing space.
Should you need a real space in the URL, use the
+ character to represent a space. For example,
&DV0=foo+bar to assign the
DV0 parameter to