Could not add to the list "Customers" because the list contains the maximum number of items.

You can merge QuickBooks customers

Problem

You can no longer add new customers to QuickBooks

Description

Each version of QuickBooks allows a certain number of customers. For Enterprise, it's 100,000. For other versions, it's 14,500.

Solution

Customer Matching

We recommend switching your customer matching to single name. This will ensure all orders enter a single customer:

1. Login to Connex.
2. Click manage.
3. Expand customers.
4. Choose single name as the match.

Merge Customers

Yes, you can merge two different customers in QuickBooks Desktop. Here's how:

1. Right-click the name of the customer that you would like to merge, then select Edit Customer.
2. Replace the customer name with the one you took note of or copied, then select OK.
3. A prompt will appear, select Yes to proceed with the merge.

However, you'll have to make the job a parent customer first before it can be merged into a different customer. Just place your cursor on top of the small diamond symbol before the name of the job. Then, drag it to the left side. 

You can also double-click on the name of the job. Then, delete the information in the Customer field before clicking OK. 

Once done, follow the same steps on how to merge customers. You can also check out this article for more details: Merge Accounts, Customers, and Vendors.

In addition, you can also save this guide just in case you need to run sales or customer-related reports: Customize customer, job, and sales reports in QuickBooks Desktop.