If an item has existing metadata content that is not in the ArcGIS metadata format, the current version of ArcGIS for Desktop can't use that information. For example, the ArcGIS metadata editor and the Export and Validate buttons only work with content that is stored in the ArcGIS metadata format. When you use the Import button, the metadata content you are importing is converted to the ArcGIS metadata format.
If an item has existing metadata in the ESRI-ISO format that was typed by a person, it is upgraded automatically to ArcGIS metadata when you view it on the Description tab. If an item has existing metadata in the FGDC format that was typed by a person and no ArcGIS or ESRI-ISO metadata content typed by a person, you will be notified that your FGDC metadata must be upgraded to the ArcGIS metadata format before it can be used on the Description tab.
Click Yes to upgrade the existing FGDC metadata content right away. The Upgrade Metadata tool opens and the Upgrade Type is automatically set to FGDC_TO_ARCGIS. If you would rather wait, click No.
An Upgrade button 
will be available on the Description tab. You can use it later to upgrade the item's metadata following the instructions below.
Learn more about upgrading FGDC metadata
If you prefer to upgrade metadata for many items at once instead of one at a time, run the Upgrade Metadata tool in batch mode or with a Python script using the appropriate upgrade type. For example, you might upgrade metadata for all items in a folder or geodatabase.
- In the Catalog window, click the item whose metadata you want to upgrade.
- View the item's metadata.
- Click the Upgrade button .
The Upgrade Metadata tool opens.
- Specify the appropriate Upgrade Type based on the format of the existing metadata that you want to upgrade.
- ESRIISO_TO_ARCGIS upgrades existing metadata in ESRI-ISO format to ArcGIS metadata. ESRI-ISO metadata was typically created with the ISO metadata editing wizard provided with ArcGIS Desktop 9.3.1 or earlier releases. There is no need to use this option when upgrading metadata from the Description tab. Existing ESRI-ISO metadata will be upgraded automatically when you start editing an item's metadata.
- FGDC_TO_ARCGIS upgrades existing metadata in FGDC format to ArcGIS metadata. FGDC metadata was created with the 9.3.1 FGDC metadata editor, the default metadata editor provided with ArcGIS Desktop 9.3.1 or earlier releases. FGDC metadata may also have been created outside of ArcGIS. The Upgrade button only appears on the Description tab when an item has existing FGDC metadata typed by a person that hasn't yet been upgraded, and new ArcGIS metadata content hasn't been saved on the Description tab. Typically, this is the choice you want to make.
- Click OK.
After the Upgrade Metadata tool has finished running, it is unlikely that the item you selected in the first step will continue to be selected in the Catalog window. The behavior of the geoprocessing system depends on the ArcGIS for Desktop application and your environment settings. For example, in ArcCatalog, the folder or geodatabase containing the item whose metadata was upgraded will usually be selected.
- Click the item again in the Catalog window to see its upgraded metadata.
The Upgrade button no longer appears on the Description tab.