The first 90 days after an ERP implementation are often when long-term success is determined. This is the period when users form habits, new processes are put to the test, and small issues either get resolved or grow into larger operational challenges. It’s also when organizations begin to see whether the system is delivering the business value that justified the investment in the first place.

Some companies use this stabilization period to build momentum, improve adoption, and lay the groundwork for continuous improvement. Others struggle with workarounds, declining user engagement, and unmet expectations that can linger for months or even years.

In this article, we’ll look at some of the most common mistakes organizations make during the first 90 days after ERP go-live, what successful ERP adoption looks like by day 90, and how to transition from stabilization mode into ongoing optimization and business growth.

 

What Are Common Mistakes in the First 90 Days and How Can You Avoid Them?
During the early post-go-live stage, certain pitfalls come up so frequently that they can almost be considered industry clichés. Recognizing and avoiding them will save you a lot of headaches:

1. Assuming Go-Live Means “Done”: The classic mistake is declaring victory on Day 1 and disbanding the project team. Maybe there’s a celebratory email from leadership that unintentionally signals we’re finished. This can leave the organization unprepared for the wave of post-go-live support needs. Avoidance strategy: Keep key project resources (internal and partner-side) engaged during the first few months, and explicitly communicate that the project is now in its stabilization phase.
2. Underestimating Support Needs: Even if you have IT support, an ERP is a different beast. Immediately after go-live, your helpdesk may get a flood of new types of issues. If you haven’t bolstered support for this phase, users might get frustrated with slow response times. Avoidance strategy: Put a dedicated support plan (hypercare) in place for the immediate weeks after go-live, ensuring quick responses to critical issues. This might mean temporary assignment of additional IT staff or continued involvement of partner consultants.
3. Poor Communication & Lack of Transparency: If users don’t know where to report issues or never hear status updates, small problems can breed frustration. Avoidance strategy: Establish clear communication channels and regularly update the organization on the status of stabilization, what’s being fixed, and the plan.
4. Neglecting Continuous Training: One-time training before go-live isn’t enough. Without reinforcement, users can slip back into old habits or use shadow systems (such as Excel) when they get stuck. Avoidance strategy: Keep offering bite-sized training and refreshers during the first few months, targeted to areas where you see confusion. Also, encourage peer learning, in which proficient users help those who are struggling.
5. Rushing to Customize or Extend: Eager to realize more value, some teams immediately start customizing the system or enabling new modules. This can distract from core adoption and potentially introduce new issues. Avoidance strategy: As discussed above, wait until you’ve stabilized core functions before diving into significant enhancements. Have a separate “improvement backlog” to capture ideas for later, so people feel heard but not every idea is acted on immediately.
6. Ignoring Process and Governance: In the rush of post-go-live, some teams bypass the governance mechanisms established during implementation. For example, they might let departments make on-the-fly process changes or system tweaks without broader review. Avoidance strategy: Stick to the governance and change-control processes you established during implementation so that changes remain aligned with your overall goals. This ensures early fixes or adjustments don’t inadvertently undermine the integrity of the solution.

By anticipating these pitfalls, you can take proactive steps to mitigate them. The common thread in all of these mistakes is a lack of intentional post-go-live management. Remember, ERP success is determined as much by what happens after go-live as by what happens before.

 

What Does Success Look Like by Day 90?
By the end of the first 90 days, success won’t mean “everything is perfect”. That’s unrealistic. Instead, think of success in terms of progress and stability:

• System Reliability: Your ERP is now running all critical business functions with confidence. The system is stable (major bugs resolved), and performance is meeting expectations (no severe slowness or downtime). Core processes like order processing, invoicing, and financial close are being executed in the new ERP routinely without major setbacks.
• User Proficiency: Users have moved from initial learning mode to a reasonable level of self-sufficiency. They know how to do their primary tasks in the system, and they trust it. You might measure this by seeing fewer basic “how-to” support tickets by day 90 and more advanced questions or suggestions. This is a sign that users are getting comfortable and thinking about enhancements rather than just coping.
• Adoption and Compliance: Most employees are using the ERP as the single source of truth for their work (e.g., entering data in the ERP, not in old spreadsheets). If you track usage metrics, you should see high login rates and transaction volumes relative to expected activity, indicating minimal work outside the system.
• Resolved Issues: Most post-go-live issues have been identified and either solved or have clear resolution plans. Your support logs might show that ticket volumes have declined from the peak at go-live down to a normal baseline, and that open issues are trending downwards.
• Leadership Confidence: Executives and managers feel comfortable that the ERP is under control. Key performance indicators (KPIs) may indicate improvement (e.g., shorter month-end close times, faster order fulfillment times), although they may not yet be fully optimized.

In simpler terms, success at day 90 means you’ve stabilized and built the foundation for further achievements. The organization isn’t questioning “Was this a mistake?” Instead, the mindset is, “The hardest part is behind us, now how do we maximize value?”

 

What Comes Next After Stabilization?
After the first 90 days, you should have a stable platform and a workforce that’s over the initial hump. This doesn’t mean the journey with your ERP ends. In fact, this is where the fun part begins: turning a stable system into a continuous improvement engine for the business.

Post-90 days, the focus typically shifts to:

• Long-Term Optimization: With stability achieved, you can revisit the improvement backlog and start executing on enhancements. This could involve rolling out new modules or features that were deferred during initial go-live, fine-tuning processes for efficiency, or adding automation and integration to reduce manual work.
• Ongoing Training & Development: Keep nurturing user skills. Technology evolves, and there are always new capabilities to learn and leverage. Some organizations establish a “center of excellence” or a regular user group to champion best practices and share tips. This is part of treating your ERP as a dynamic system you continuously learn from.
• Periodic Reviews & Governance: Maintain aspects of your governance structure for the long run. Maybe it’s quarterly steering committee reviews of system performance and business results; maybe it’s a standing “ERP optimization” meeting where suggestions and pain points are discussed. Having a periodic forum ensures the ERP continues to align with business changes and that small issues don’t fester unseen.
• Strategic Roadmapping: Now that you’re through the thick of it, step back and actually plan what’s next. What additional modules, advanced analytics, or process improvements could further drive value? This is where you look beyond stabilization to more transformative opportunities. Think of it as entering the next phase of your ERP journey, where you’re not just preventing problems, but actively expanding capabilities and benefits.

Finally, remember that in an effective ERP journey, implementation isn’t a one-off project. It’s the start of a continuous evolution of your business. The organizations that achieve the highest ROI from ERP are those that continue investing in their systems and people long after go-live. They treat the first 90 days as a springboard for ongoing improvement, not just an obligation to be managed.

 

Final Thoughts
This post-go-live phase can feel like a mix of relief and new pressure. You’ve arrived at go-live after a lot of arduous work. Celebrate that achievement! But as we’ve explored, the first 90 days are about solidifying that win into lasting success.

By focusing on stabilization, supporting your users through the adjustment, and consciously managing this period, you lay the foundation for the improvements and benefits you originally set out to achieve.

In our experience at OTT, companies that treat the first 90 days as seriously as they did earlier project phases tend to reap much greater long-term rewards. They emerge from the go-live transition not just with a working system, but with an engaged workforce, refined processes, and a clear roadmap for continued improvement.

As you conclude this series and embark on (or continue) your own ERP journey, keep in mind that every stage, from planning and selection to implementation and stabilization, is connected. ERP success is cumulative. If you find yourself needing guidance at any stage, it often helps to talk with peers or a partner who’s navigated these waters before. Even a brief conversation with an experienced ERP advisor can validate your approach, reveal blind spots, and boost your confidence that you’re doing the right things in each phase.

Thank you for following this series. Here’s to a stable, successful first 90 days, and to making your ERP investment a true engine for growth and efficiency for years to come!