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Error code 400 when creating a new customer - customer number already in use

You try to create a new customer in Assist and get error code 400, or a message saying the customer number is already in use. The customer is not saved.

Written by Leif T. Rudlang

Cause

Assist and your finance system share the same customer number series. The error occurs when Assist tries to assign a customer number that already exists in your finance system - typically because:

  • the system auto-assigns the next number, but the next free number in the finance system's series clashes with a number already imported from a customer or supplier, or from a different number series, or

  • the number series in Assist and the automatic generation setting in the finance system are out of sync.

So Assist's own help text about a customer number already being in use is usually about a clash between the customer and supplier series - not about your particular customer already existing.

Solution

Option 1 - Enter the customer number manually (quick fix)

If you do NOT have any integrations, always use this one!

  1. Open the customer in Assist.

  2. Under Customer number, select Enter customer number manually instead of Set by Tripletex.

  3. Enter a free number. Assist shows the next available customer number as a guide. Then choose Save customer. The customer is saved in Assist and given the correct number.

You will find the setting in Assist under Settings -> Finance (example below)

Option 2 - Let Assist or the finance system assign the number automatically

In Tripletex, go to Customer - Customer settings -> Settings for new customers/suppliers.

In PowerOfficeGo, go to Menu - Settings - Accounts receivable

  1. Check that Automatic generation of customer numbers is enabled.

  2. Make sure the number series is set so that the next free number does not clash with the existing customer or supplier series.

  3. Save, then create the customer again in Assist.

How to avoid this in future

When you add a business customer that also exists as a supplier in the finance system (for example Tripletex), check that you do not end up with duplicate entries. Pick the right number series from the start and you will avoid clashes.

Still having problems?

Send us a screenshot of the error message and the name of the customer you are trying to create, and we will take it from there.

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