If i add a new inventory item or make changes to an existing one, it will NOT save. Says error

We don't want you to experience this, @useronsitefleetinc. Let me help you fix the issue with the inventory function on your QuickBooks Online (QBO).

The first thing I can suggest is to refresh your browser. If the issue persists, open your browser's private window. It allows you to isolate the cache, which is the common cause of unusual behaviors.

Here are the shortcut keys:

• Mozilla Firefox and Microsoft Edge: Press Ctrl + Shift + N
• Google Chrome: Press Ctrl + Shift + N
• Safari: Press Command + Shift + N

If that works, return to your regular browser and clear its cache. Otherwise, open an alternative browser that's available for you. 

For more information, you can visit this article to help you manage and track the items that you buy and sell in QBO: Set up and track your inventory.

Additionally, you may want to see available reports that will help you see the product cost, the product on hand, and more in QBO: Use reports to see your sales and inventory status.

I'll be right here if you have further questions while working with inventory or any QuickBooks queries. Keep safe and have a good one.