Altium Designer Documentation

Unique Identifiers Errors

Modified by Jason Howie on Aug 7, 2017
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Parent category: Violations Associated with Documents

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This violation occurs when two circuit elements (including Ports, Sheets, Components, Component pins, Sheet symbols, parameters, etc) - across source schematic sheets in a design - have the same Unique ID associated to them.

Note that the compiler does not detect duplicates of connectivity-independent UIDs, such as those for Parameter Sets for example. However, duplicates of these UID types are automatically corrected when a document is loaded.


If compiler errors and warnings are enabled for display on the schematic (enabled on the Schematic - Compiler page of the Preferences dialog) an offending object will display a colored squiggle beneath it. A notification is also displayed in the Messages panel in the following format:

Unique Identifiers Errors: found at <Location1> and < Location2>


  • Location1 is the X,Y coordinates for the first object found with a Unique ID error.
  • Location2 is the X,Y coordinates for the second object found with a Unique ID error.

Recommendation for Resolution

Reset the Unique ID's for the offending objects as required. This can be done on a global level using the Tools » Convert » Reset Component Unique IDs command. This command encompasses two processes, which are effectively performed in sequence:

  1. Duplicate UIDs are detected within the design and corrected by resetting (regenerating) the UID value for one of the objects in the duplicate pair.
  2. The UIDs for Parts and Sheet symbols are reset (regenerated).

Note that the command can be applied to the active document, all source schematics in the active project, or all open schematics (regardless of the project to which they belong).


  1. With the exception of component UniqueIDs, duplicate UIDs are automatically detected and corrected when a Schematic document is loaded in Altium Designer, thereby removing the need for user intervention. The detection/correction process works through all UIDs in the design, including Set Parameters and parameter additions to Ports, Nets Labels, Directives, Sheets and so on. This correction is important for Parameter UIDs in particular, where duplicate UIDs can cause obscure Rule misbehavior and annotation errors in projects with Variants.
  2. Components that have duplicate UIDs are not processed by the automatic correction on document load. Component UIDs are fundamental to design connectivity, and any duplicate UIDs (which are very unlikely to occur) are best resolved by intention when detected by the Compiler.
  3. When any of the corrective measures have been applied to resolve duplicate UniqueIDs - multiple or automated UID changes - the related Schematic-to-PCB links need be reinstated to maintain design connectivity. Use the PCB editor’s Edit Component Links dialog to perform the required updates (Project » Component Links).


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