Resolving ResizeObserver Message in AMCalc 3 for Salesforce

3 Creeks introduced graphing with the release of AMCalc 3 when viewing a saved schedule or using the schedule compare tool. To render the graphs on screen, the popular and well-established JavaScript library ChartJS was added to the AMCalc package and is automatically installed with AMCalc into your Salesforce system.

If you are on AMCalc 3.3 or later and your Salesforce instance was created before the Spring ‘23 release of Salesforce, you my encounter the error message “ResizeObserver is not a constructor” when you try to generate a graph in AMCalc. To resolve this, follow the steps below.

• Navigate to the Setup screen and type “Session Settings” into the quick find box

• Find the section titled “Lightning Web Security” and check the box for “Use Lightning Web Security for Lightning web components…”

• Scroll to the bottom of the Sessions Setting page and click the Save button.

• Lastly, log out off of Salesforce and clear your web browser’s cache.

That’s it!

By default “Use Lightning Web Security for Lightning web components…” is pre-selected for newer Salesforce instances, but for older instances it needs to be manually selected. To read more about Lightning Web Security check out this Salesforce documentation.

If you are still seeing the message after clearing your browser’s cache, email support@3creekstech.com.

To learn more about AMCalc, go here.