TrimbleSessions layer is missing some mandatory fields."

Last Published: April 25, 2020

Error Message

“TrimbleSessions layer is missing some mandatory fields.”

This error message displays in the Trimble Positions Desktop add-in version 10.1 in ArcMap, namely the Trimble Positions Desktop Administration window. The Trimble Positions Desktop add-in is used in conjunction with the Trimble Positions ArcPad Extension or Trimble Positions Mobile Extension.

After clicking on the ‘Enable Geodatabase’ button to create the TrimbleSessions feature class, and clicking ‘Run Tests’ from the GNSS Enabling dialog box, the error displays in the ‘Compatibility Testing’ window. In this case, the compatibility test is performed against the Trimble Positions Mobile Extension.


The TrimbleSessions feature class was generated in a personal geodatabase that contains an invalid field in the attribute table called "Note_".
The word "Note" is considered a Microsoft Reserved Word, and cannot be used in any field name since a personal geodatabase (or .mdb file) is a Microsoft Access database type.

Due to this Microsoft limitation and because the default mandatory schema for the TrimbleSessions layer requires the Note field, the field is generated with an ‘_’ underscore at the end.

Although the field is present in the TrimbleSessions attribute table, because it is called "Note_" and not "Note", the Trimble Positions Desktop add-in considers the field to be missing.

Solution or Workaround


Follow the workflow in the link below. Store the data in a personal geodatabase and migrate the data to a File Geodatabase (.gdb file).

Migrating to a File Geodatabase

The issue is not reproducible if the user clicks ‘Enable Geodatabase’ using a File Geodatabase, and clicks the ‘Run Tests’ button in the GNSS Enabling dialog box.

When the attribute table is opened for the corresponding TrimbleSessions layer that is generated, the 'Note' field is created successfully. The File Geodatabase is not a Microsoft database format, and is therefore not limited by reserved words.


Upgrade to the Trimble Positions Desktop add-in version 10.2.

Trimble Positions Desktop add-in

Article ID:000011936

  • ArcPad 10 0
  • ArcPad 10 2
  • ArcMap

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