What your DCP verifier is actually telling you.
Each page here takes one real verification error, explains the mechanism behind it, and says what to do. The quoted messages are the strings DCP-o-matic's verifier emits, checked against version 2.16.91.
No valid ASSETMAP or ASSETMAP.xml was found
Your DCP verifier cannot find the ASSETMAP. Usually the wrong folder was selected, or the top-level files were left behind in a copy. How to tell which.
The hash of an asset does not agree with the PKL
A DCP hash mismatch means a file changed after packaging. Usually an interrupted copy or a cloud sync. Why re-exporting is rarely the answer.
No packing lists found in asset map
The ASSETMAP is present but names no PKL, so a DCP verifier has nothing to check assets against. What that means and how to recover.
Unresolved reference to asset id
A CPL references an asset that is not in the package. Often this means you have a VF supplemental without its OV, not a broken DCP.
An XML file is badly formed
A DCP's ASSETMAP, PKL, or CPL will not parse. The line and column in the error tell you whether it is truncation or an editor's damage.
More than one asset with the same ID
An ASSETMAP or PKL lists the same UUID twice. Usually two packages were merged into one folder. Why this is not safely repairable.
The ASSETMAP references a file that is not there
The ASSETMAP names a file the package does not contain. Nearly always an incomplete copy. How to identify which assets are absent.
The file is a different size than the packing list says
A DCP asset is a different size than the packing list declares. The file is truncated or was modified. Why this is worth catching before hashing.
Why we publish these
Most DCP failures are package plumbing rather than anything creative, and the error text alone rarely says which of several causes you have. We check packages for a living, so writing down what each message means costs us nothing and saves somebody a night.