ERP user acceptance testing (UAT) is the test phase in which the business itself confirms that the new system lets it do its real work. The difference from unit and integration testing is the question: not "does the system work?" but "can we do our job with this system?" The go-live decision rests on its outcome.
Entry criteria: when does UAT start?
- Integration testing is complete with no critical defects left
- The test environment has near-production configuration and representative data (ideally from a mock load)
- User authorisations are set up with real roles
- Test users have been trained
How to write scenarios
Good UAT scenarios test end-to-end processes, not individual screens. Instead of "create an order", for example: "take a foreign-currency order from an export customer, deliver, invoice, check the receivable, see the profitability". Scenarios should be linked to the requirements from the fit-gap analysis, proving that every requirement was tested.
Each scenario states its preconditions, steps, test data, expected result (document, amount, accounting entry) and the responsible user.
The happy path is not enough
Real life is full of exceptions. UAT must also cover:
- Returns, partial deliveries, price differences and cancellations
- Credit limit breaches and approval flows
- Month-end closing steps
- Attempts at unauthorised transactions (authorisation checks)
- Whether reports give the business the results it expects
Defect management
Every defect is logged in a single list and prioritised: critical (process stops, no workaround), high (workaround exists but is costly), medium and low. A fixed defect is retested by the user who raised it. Items that are "not a defect but a new request" are listed separately and go through change management.
Exit criteria and sign-off
UAT ends on criteria, not on a date: all critical scenarios pass, no open critical defects, and an approved workaround for every high-priority defect. Each process owner gives written sign-off for their area. That sign-off is the basis of the go-live decision.
Common mistakes
- Letting the consulting team run UAT while the business just watches
- Preparing test data at the last minute
- Relaxing exit criteria under schedule pressure
UAT is the moment the project is handed to the business. For an ERP manager or project lead, the key task is making sure it is truly done by the business, with realistic scenarios.
