When launching a workflow to approve data in the PLM, a precondition report is ran to ensure that the data is in a suitable state and all the workflow pre-requirements are met.
If the report finds an error, this must be resolved before the workflow can be launched. 

Below details some of the common causes of the errors, and how to fix them:

• Checking control rules
  
  
  The control rules (defined via the design code) must be the same for all Parts
  • Commonly this is caused because no design code is defined for one or more of the affected Parts (therefore no control rule). Check below further in the report for the 'check design code' section, and assign a design code to any Part with a missing one (see bullet point below).
  • If like the second image, its caused by two or more different control rules being defined, you must split up the workflow. Firstly launch and complete another workflow for the Part with the differing control rule, then resume the original workflow to approve the remaining objects.
     
• Checking Design Code
  
  All objects must have a design code assigned
  • Assign a design code to all the Parts without one (the CADs & Documents will inherit from its Parent Part).
     
• Not latest version versions
  
  In preparation documents that will be impacted by the workflow must be the latest version
  • Check the status of all the objects in the Check dependency  tree to find how the non-latest version is linked to the structure. If its parents are all in preparation, then you need to update the structure.
  • Note often this can be caused because a drawing has not been updated and it still pointed to the non latest 3D version.
  • If its parent is Approved or Replaced, then contact PLM Support as it can either be due to a migration or data quality issue in SmarTeam.
     
• Drawing save date
  
  A drawing must be saved after the pointed 3D document
  • Update the parent object (drawing) so the latest update on its dependency is taken into account.
     
• Checking state of collected items
  
  Objects can not already be 'in review' state via another workflow
  • Complete the outstanding workflow to either approve or reject the concerned Part/CAD Document first.

Complete documentation: Design Verification Workflow FAQ