ERP integration: five mistakes that cost more than the whole project

“We’ll just connect it to the ERP” is a sentence that makes an experienced project manager sit up. Connections to other systems are the most underestimated part of business software development: a small part of the budget, but most of the problems.

Five classic mistakes

1. 01Nobody looked at data quality, and the ERP contains thousands of duplicate customers.
2. 02Synchronisation “once a night” for a process that needs the data immediately.
3. 03No plan for downtime: the ERP goes down for maintenance and orders fall into a black hole.
4. 04A connection with no owner: when a code list changes, nobody knows for three months why the prices don’t match.
5. 05“Everything to everything” connections: a fifth system connected to the four previous ones means ten connections to maintain.

Connecting systems is the core of digitalising a business. If it’s done badly, no new application will change that.

How to do it right

One integration layer through which systems communicate, instead of connecting everything to everything. A message queue that holds data when a system is temporarily unavailable. Monitoring with alerts, and a named owner for every interface in the contract. It sounds more expensive — until you add up the first weekend outage of invoicing.

One word that will save your weekend: idempotency

The most common silent integration error: the same order is recorded twice when a request is retried. The solution is idempotency. Every operation has a unique key, so repeating it doesn’t break anything. It sounds like a developer detail, but it decides whether, after a network outage, you have order or duplicate invoices. Ask your vendor how they handle repeated and delayed messages.

How to test a connection before it catches fire

A connection that has only been tested on “nice” data will fail in its first real month. You need to test the bad scenarios too: an ERP outage, incomplete data, a changed code list, double the load. Better to find the problem in a test environment than on a Friday evening during month-end closing. Resilience isn’t built after an incident, but before it.

A connection sounds like a line item in the budget. In reality, it decides whether the system will work even in the worst week of the year. Ask about it in the quote as closely as you ask about features.