Probably because it is being assigned by the EPDM add-in in SolidWorks so that the file can be named according to the part number. Then, if it fails to add to the vault it is treating it as a new part and assigning a part number (from data card setting) - like copy paste directly into the vault.
We removed this issue by NOT assigning a part number (serial) on the data card but by having an add-in that triggers on the first transition in the workflow (automated) to assign a part number IF it does not exist or IF it does exist but doesn't follow certain rules....
Sounds like an interesting solution, Tim, but what really concerns me is understanding why a particular file would consistently fail to be added. I feel like I need to have a handle on what might cause such behavior and whether we could avoid it by building our assemblies differently or something...
Found the answer via a tiptoe through the KB tulips:
Save As of assembly containing internal components fails with 'Failed to add the new file to the vault. 'An unspecified error occurred.'.
Reproduced using EPDM 2011 SP4, SW 2011 SP4, Windows 7 x64 & EPDM 2012 SP0, SW 2012 SP0, Windows 7 x64 Can repro on any assy with internal components. 1. Create new assembly, save. 2. Insert, new part (as internal component). 3. File, Save as, save fails adding assembly with error:
Failed to add the new file to the vault. Description = 'An unspecified error occurred.'
The saved assembly remains local and has to be added manually (RMB, Add to vault).