If you have X9.0 / X9.1 / X9.1.1 you will receive a message to update to X9.3.+. Follow the prompts to download and install.
If you have X9.2 installed and check for updates it will tell you that EndNote is already up to date. It will NOT show the update to X9.3.
Follow this link for instructions to manually download and install the patch.
If you already have Catalina installed, then older EndNote versions will not run. You will need to re-install X9.3. If you have a site licence copy you will need to obtain the new installer from your Institution.
If you have saved your library as a package: .enlp, you will first need to extract the library from the package to convert.
In Finder > right click on the .enlp file or press and hold the ‘Control’ key and left click and select show Package Contents.
Copy and paste / Drag and Drop the .enl file and .Data folder to the location you wish to save your library.
Recommend you do not save your library as a package.
Make sure that your library is NOT saved on a network drive or in iCloud. See moving to safe location.
After updating to X9.3, you will need to convert your library to the new 64bit format. EndNote will make a converted copy. Note that older versions of EndNote will not be able to open a library created in X9.3+. You can use sync to move your data to different systems and or older versions of EndNote.
If you have your library set to automatically open in your preferences, change it open the most recent. Then once the library conversion is complete you can change it back. Edit > Preferences > Library. (Otherwise EndNote will keep trying to open the older file and convert it).
The original library will remain in the original location.
Click Yes to continue.
In the Save As: dialogue, EndNote suggests the original library name and adds the suffix "-Converted"
You can change the name to anything but make it obvious this is the new version, use a meaningful name for your libary like MasterLibrary-Converted, try to stay away from MyEndNoteLibrary the default name used by EndNote.
If you are syncing your library to EndNote Online, DO NOT make any changes to the library. Save the converted library to a safe location. Back-up and sync.
You will be warned that this is a different library. Click OK and sync. No changes should be made.
If you want to share or move / copy your library to a Windows machine you will need X9.3 installed on that machine. Else you will need to either share the library with EndNote Online or Sync to your own Windows machine if using an older Windows version.
Some users only see the EndNote Online tab in Word after updating to Catalina and / or updating Word.
This link: Word add-in changed to Online