If you are currently using an External Client App, please skip this section and go to Step 2.  If you are currently using a Connected App, you will want to take this opportunity to transition to an External Client App, as Salesforce no longer recommends using Connected Apps now that External Client Apps are an option. 

Please navigate to the app by navigating to Salesforce Setup (1) | Apps | Manage Connected Apps (3), and open the Connected App you use with your Vicasso product.  Once there, you can click the 'Migrate to External Client App' button; this will automatically convert your legacy Connected App into a new External Client App.

You will need to create a new Self-Signed Certificate to be used, as you are unable to 'renew' expired ones.  The most efficient method here would be to delete the expired certificate and create a new one allowing you to use the same name.  If you do not delete the current one, you cannot use the name again.

1. Navigate to Salesforce Setup | Security | Certificate and Key Management
2. Click 'Create Self-Signed Certificate'

3. Input the required values
   1. Label = "Vicasso Apps"
   2. Unique Name = "Vicasso_Apps"
      1. This will auto-populate based on your Label
   3. Exportable Private Key = True 
   4. Key Size = 4096
      1. This determines how long it takes for your certificate to expire.  2048 expires in one year, 4096 expires after 2 years.
4. Click 'Save'
5. Once the new certificate page loads, click 'Download Certificate' and save it for future use.

With your newly created self-signed certificate created, we just need to attach it to your External Client App. 

1. To do so, navigate to Salesforce Setup | External Client App | External Client App Manager
2. Click into the External Client App that matches the certificate name, in this example 'Vicasso ALL'
3. Select the 'Settings' tab
4. Click 'Edit' on the right hand side of your screen
5. Scroll and expand the 'OAuth Settings' then find the 'Flow Enablement' section
6. Under 'Enable JWT Bearer Flow' you will upload your new certificate with the 'Upload Files' button.
7. Hit 'Save' at the bottom of your screen