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Peppol e-Invoicing Launch in Belgium: Lessons Learned After Two Months

  • Writer: Mathieu Pasture
    Mathieu Pasture
  • 6 days ago
  • 3 min read

On February 24th, 2026, during the Peppol Service Providers Forum, we reflected on the first months following the Peppol e-invoicing launch in Belgium.

While the rollout marks a major milestone for digital invoicing, the reality of live operations shows that the situation is not as positive as we would like.


Over the past two months, we have:

  • Identified recurring issues related to registration data quality

  • Corrected numerous errors in our own systems

  • Observed a wide range of errors in the systems of others

  • Experienced an estimated ~1% of problematic exchanges


At first glance, 1% may seem small. However, in a high-volume production environment, that percentage represents a significant number of disrupted invoice exchanges, several hundred thousand.

In this article, we summarize the key transmission issues encountered since go-live and share observations from the field.


Mathieu Pasture Peppol

What Transmission Errors Are You Seeing?

During the session, we asked Peppol Service Providers participants:

What transmission errors are you encountering?

Participants were invited to share:

  • By speaking live

  • Through the Teams meeting

While preparing for the forum, Mathieu Pasture, our PeppolEDGE CTO expert in Peppol, identified at least 20 distinct types of issues and the live feedback confirmed that these were widely experienced across providers.



The Most Common Peppol Transmission Issues Observed

Below is a structured overview of the issues reported across the network.


Infrastructure & Connectivity Issues

These errors relate to availability and infrastructure stability:

  • SMP unreachable

  • Access Point unreachable

  • Timeouts

  • HTTP redirects

  • HTTP 500 errors

  • HTTP 503 errors

  • Use of HTTP for SMP lookup (instead of HTTPS)

  • Soap Rejection because of duplicates

These issues often create uncertainty:

  • Is the receiver down?

  • Is the SMP incorrectly configured?

  • Is there a network-level issue?

Even temporary instability can trigger retries, duplicate attempts, and increased load across the ecosystem.


Certificate & Security Problems

Security configuration errors have been more frequent than expected:

  • Test certificates used in production

  • Invalid certificates (SMP or Access Point)

  • Invalid signatures

  • Invalid AS4 response


In some cases:

  • Production traffic was routed using test credentials.

  • Certificate chains were incomplete or misconfigured.

  • Signature validation failed due to incorrect key usage.

These problems immediately block message exchange and require coordination between service providers.


Validation & Document Errors

A significant category involves content and structure validation:

  • Schema validation errors

  • Schematron validation errors

  • SBDH not matching

  • Invalid MLR / IMR

  • Unexpected Process ID or Document Type

  • Unexpected Participant ID

These issues often stem from:

  • Misaligned implementation guidelines

  • Incorrect profile configurations

  • Differences between declared and actual document types

  • Registration inconsistencies in SMP

In many cases, the sender believes the document is valid, but receiver-side validation rejects it.


The Bigger Issue: Registration Data Quality

One of the root causes behind multiple error categories is inaccurate or inconsistent registration data.

Problems observed include:

  • Incorrect participant IDs

  • Wrong process identifiers

  • Misconfigured document type identifiers

  • Incomplete or outdated SMP registrations

Improving registration data quality will likely reduce a significant portion of the ~1% problematic exchanges.


What We’ve Learned After Two Months

Everyone Had Fixes to Make

No system was perfect at launch. All of us corrected issues on our own platforms.


Interoperability Is a Shared Responsibility

Errors rarely sit entirely on one side. Coordination between Access Points and SMP providers is essential.


Small Percentages Still Matter

At national scale, 1% represents real operational impact for businesses.


Transparency Helps the Network

Open discussions, like those at the forum, accelerate improvements.


Peppol moving forward

Moving Forward

The Belgian Peppol launch is a success in terms of adoption and momentum. However, stabilization is still ongoing.


Key improvement areas:

  • Strengthening validation before production deployment

  • Better certificate lifecycle management

  • Improved SMP registration controls

  • Clearer alignment on process and document identifiers

  • Faster error diagnostics and feedback loops


The ecosystem is learning quickly. The first two months have already resulted in significant improvements across providers.


Final Thoughts

The Peppol network is built on interoperability, but interoperability requires precision.

The February 24th forum discussion demonstrated something important:

We are not facing isolated incidents, we are facing shared growing pains of a live, large-scale e-invoicing ecosystem.


By continuing collaboration and open communication, Belgium’s Peppol implementation will mature into a highly stable and reliable infrastructure.


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