Page Comparison

...

1. Create an Apex class that implements the System.Callable interface. For an example, see the code below.

2. Click on Setup and search for Custom Settings

3. Click on Manage next to System_Settings

4. Click New

5. For the name specify Calendar Context Menu Class

6. Enter the name of the Apex class from step 1 into the String value field

7. Click Save

Troubleshooting

While configuring your custom context menu, an error that you might run into would be 'class could not be instantiated:' (followed by the class name you entered in step 6 of the previous section). There are two common reasons for this:

1. You did not enter the correct class name into the custom setting. See step 6 of the previous section. Make sure to copy paste the class name to eliminate any spelling errors. Make sure there are no starting or trailing spaces.

2. The class does not correctly implement System.Callable. Make sure that it does, and that the class compiles without errors when you save it. Make sure to review the official Salesforce documentation: https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_interface_System_Callable.htm

Callable class parameters and return type

...