ArcGIS Pro: Requested operation could not be completed

Error Message

In ArcGIS Pro, attempts to apply, change, rename, or reorder symbology in the Symbology pane fail and return the following generic error message:

Error:
Requested operation could not be completed.

Although this message seems generic, it only occurs in the Symbology pane and is specific to ArcGIS Pro symbology workflows.

Cause

• Edits made on the feature classes are not saved properly before applying symbology.
• Feature classes are stored in an enterprise geodatabase instead of a file geodatabase.
• There are null values in the field.
• Symbology is applied to feature layers with a temporary join.
• An earlier version of ArcGIS Pro is used.

Solution or Workaround

The simplest solution is to close and re-open the Symbology pane. However if this does not resolve the issue, use one of the options below, depending on the cause.

• Save any changes made to the feature classes before applying symbology.
• If data are stored in an enterprise geodatabase, export the data to a file geodatabase and symbolize the feature classes from the file geodatabase. Refer to ArcGIS Pro: Export data for instructions to export any type of data to a geodatabase.
• Replace the null values with zeroes. To do so, refer to How To: Replace null values with zeroes in an attribute table in ArcGIS Pro.
• When joining feature layers or tables, ensure the layers or tables are joined permanently before applying symbology. To make a permanent join, use the Join Field tool or use the joined layers as input to either the Copy Features, Copy Rows, Export Features, or Export Table tool.
• Upgrade to the latest version of ArcGIS Pro. For more information, refer to ArcGIS Pro: Update ArcGIS Pro.

Note:
If the issue persists, contact Esri Technical Support.