Style files are missing after installing a new version of ArcMap

Description

After installing a new version of ArcMap, custom styles created by the user in a previous version are not found in the .style file of the new version.
 

Cause

When installing a new version of ArcMap, a new .style file is created during installation and is used as the default for the new version of ArcMap. The new .style file does not include the custom styles stored in the .style files of the previous version. However, previous .style files are retained in the ArcMap folder of the previous version and are not used in the new version.

Solution or Workaround

Copy the .style files from the previous version of ArcMap and paste the files in the ArcMap folder of the new version.

1. Navigate to the ArcMap folder of the previous version in the following directory:

   C:\Users\<username>\AppData\Roaming\ESRI\Desktop<previous version>\ArcMap\<username>.style

   Note:
   For Window users, enable the viewing of hidden folders to find the AppData folder. 

2. Rename the .style file (for example, <username>_OLD.style).
3. Copy the .style files from the directory.
4. Navigate to the ArcMap folder of the new version in the following directory:

   C:\Users\<username>\AppData\Roaming\ESRI\Desktop<new version>\ArcMap\

5. Paste the .style files to the folder of the current version.

   Note:
   Rename the newer version of the .style file if the file shares the same name as the style file of the previous version.

Alternatively, import the styles from the .style file in the previous version to the .style file of the new version with the Style Manager. For more information on how to import styles from a .style file, read the following documentation: Importing styles from a style file.