The Migration of legacy systems may seem straightforward in concept, take information in an older system and put it in a newer one. The process of doing this however, is anything but straightforward, and can cause a lot of headaches for your organization. While stakeholders may not look forward to this process, it’s an important step in modernizing the legacy systems and improving the utility and functionality of an organization. In this comprehensive guide, we’ll cover the basics of legacy migration, the benefits, some challenges, and the first steps necessary to beginning the migration process.

What is a legacy system?

All software participates in a lifecycle similar to our own; there’s birth, life, and death; all of this is guided by a technology aging process, which generally follows a path similar to organic life. And very much like organic life, software systems also experience a period of maximum output and value – may it be long! Once that occurs, it’s a slow and sometimes painful process of becoming less utilized, less supported, and less efficient. This is the beginning of the code rot and value decay, which will inevitably lead to the deterioration of the code that once made a piece of software so valuable.

As code rot continues, the software can eventually become a critical risk to the technological infrastructure as a whole. One wrong set of environmental circumstances could topple the entire system.

The ripple effects of a legacy system can be huge, and could have a major impact on your business.

This is where legacy systems migration comes in.Think of it as application rebirth…

What is a migration of legacy systems?

The migration of legacy systems refers to the process of transferring data, applications, and other technological assets from antiquated systems to modern ones. The migration of legacy systems covers both hardware and software transitions, but we will mainly reference software migrations in this guide. The breadth of a migration of legacy systems is expansive, covering everything from integration compatibility, platform shifts, or even replacing entire systems with a new custom version.

Reasons For Migration Of Legacy Systems


There are many reasons to conduct a legacy systems migration, including:

1. Increased efficiency
2. Reduced maintenance costs
3. Better scalability
4. Improved security

Some industries may see greater benefits than others, which you can learn more about in our 6 Industries Benefiting the Most from Legacy System Migration blog.

There are other, more specific, reasons why an organization may choose to migrate from one system to another.


You can learn more about these benefits by reading our piece on the 4 Reasons to Conduct Legacy Migration: Unlock Potential.

Roadmap For Migration Of Legacy Systems

While some common examples of a migration of legacy systems only have a few steps in the process, migration is anything but easy. The reintroduction of security risks, loss or corrupted data, and poorly planned rollout and rollback strategies can have a negative impact on your business. When beginning the process of data migration from legacy systems, it’s important to develop a detailed roadmap for your transfer.

These aren’t the only challenges organizations face when conducting a legacy migration, as potential roadblocks and pitfalls vary depending on the complexity of the move.

Enterprise level companies are likely to have more difficulties based on the sheer size of the organization, although this means they have more resources to remedy these problems. Smaller organizations have less complex migrations generally, but this comes with a smaller margin for error in their budget as well.

Some factors that may further complicate a migration process include:

1. Complexity of the legacy system
2. Compatibility issues
3. Downtime and disruption
4. Data quality and integrity
5. Lack of resources
6. Employee overwhelm

All of these factors lead to delays in conducting the migration, which can lead to real world consequences.


Recent examples show this is not merely theoretical. In January 2023, both Canadian and US national flight management applications crashed at the same time. This not only resulted in thousands of delayed and canceled flights and millions of disrupted travelers, but also put both airline crews and passengers in dangerous situations.

In May of 2022 a surge in US bond buying crashed the TreasuryDirect site.

In 2018 the IRS computer system crashed delaying the processing of millions of returns.

All of these examples were totally preventable, with government officials acknowledging the risk sometimes years before the system meltdown, and every time something like this happens the price tag for recovering the system grows.

To learn more about the risks and challenges of the migration of legacy systems read our blog Legacy System Migration Challenges For Enterprises.

Role of Technical Discovery in Migration Process

To minimize the impact of roadblocks during this process, a technical discovery may be in order.

A technical discovery is the initial first step in a migration of legacy systems with DOOR3. This preliminary step is a smaller expense and allows for our team of engineers, business analysts, and consultants to conduct a comprehensive assessment of the work required to complete a successful migration and a realistic timeline to do so.


A technical discovery also analyzes any potential risks or pitfalls that could occur during the process. This discovery phase looks at the project from a holistic perspective, and analyzes any areas within your business that may be affected by taking on the project. This may include inspecting the age of legacy systems and their last formal support offerings from developers, custom code compatibility with modern platforms, and your organization’s overall technology objectives as well as short-term and long-term goals.

Our experts build the roadmap for you, so that you know exactly how long and how much something like this will take. That way when you’ve got the resources to execute the project, you can do so swiftly and with full confidence.

Once the analysis portion of the discovery process is complete, our team shares our findings over a series of meetings. This may include recommended systems to migrate and where to migrate them to, and a roadmap for the unique migration process of your organization.

While the discovery process is unique to DOOR3, other providers have auditing processes for your systems as well. Never undercut the amount of time you provide for auditing your systems, as doing so can cause harm to your organization during the migration process.

How To Undertake Migration Process

We recognize that all these legacy system migration challenges are intimidating to the uninitiated, but migrations are a necessary reality for organizations utilizing technology stacks within their business.

Educating yourself and your team on the risks and strategies to navigate them will only result in more successful system migrations. It is possible to successfully migrate without damaging critical data, DOOR3 has helped clients to do so countless times. With a keen eye on attention to detail, organizations can improve security, flexibility, and efficiency through the modernization of technology systems.

That being said, we never advise clients to try to take this work on by themselves, even after going through a discovery phase. Bringing in third-party specialists will minimize risk of complication during the migration. Education on the process however, is still useful, empowering an organization to navigate migration conversations with ease.

To help with further educating you on the migration process, here are the five basic steps of conducting a migration of legacy systems.


To learn more about these five steps, read our blog Legacy System Modernization Approaches To Improve Software.

In this piece we also discuss three common approaches to the migration of legacy systems:

1. Replatforming
2. Refactoring/re-architecting
3. Rebuilding/replacing


A successful migration

With all these factors considered, you are ready to begin the process of upgrading your current technology stack with modern systems aiming to boost your organization’s operational capability. As the capabilities of modern technologies continue to expand, migrations will become more and more frequent, and those unwilling to adapt will be left behind.

Stay ahead of your competitors and invest in your operational technology. Reach out to us here to learn more about how DOOR3 can help you through the legacy system modernization services.

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