The right way to migrate legacy systems: Expert Q&A

Migrating a legacy system impacts daily operations, security, and integration with modern technologies. Businesses may encounter unexpected dependencies, performance issues, or workflow disruptions without careful planning. A structured approach helps reduce risks and ensures a smoother transition. Today, Ivan Ryzhik shares his experience handling migration challenges and preventing costly mistakes. ??

?Ivan, why is migrating from a legacy system challenging for businesses?

Legacy systems are often deeply integrated into a company’s daily operations. Over time, businesses build custom workflows, dependencies, and integrations around these systems. Replacing or upgrading them affects multiple processes, which makes migration complex.

Another challenge is the lack of proper documentation. When the original developers are no longer available, understanding how everything works before migration becomes more difficult.

For example, when migrating from jQuery and Handlebars to React with TypeScript, we encountered an unexpected issue - our backend relied on outdated APIs that didn’t support the necessary data formats. To bridge the gap, we developed a proxy server in Node.js to transform the data into a compatible structure. This added an extra layer of work but was necessary to ensure smooth integration without overhauling the backend immediately.

? What are the most common mistakes businesses make during migration?

The most common mistake is starting the migration without a clear strategy. Some companies try to migrate everything simultaneously, expecting a quick transition, but this often leads to extended downtime, data loss, and unexpected technical failures.

Another mistake is not assessing dependencies. Many legacy systems rely on outdated databases, custom-built components, or third-party tools that may no longer be supported. Ignoring these dependencies can cause compatibility issues that slow down or even halt the migration.

? What are the main technical challenges businesses face when migrating?

The first challenge is data migration. Businesses often deal with large amounts of data stored in outdated formats. Converting that data without losing accuracy or performance requires careful planning, especially when dealing with proprietary databases or inconsistent data structures.

Another challenge is compatibility with modern technologies. Many legacy applications weren’t designed to communicate with cloud-based services, APIs, or modern security protocols. Businesses must ensure smooth integration if the new system requires real-time data exchange with external applications. Performance issues can also arise. Older systems were optimized for on-premise environments, while newer solutions rely on cloud scalability. Without the proper infrastructure adjustments, performance bottlenecks can appear after migration.

? How can businesses reduce risks when migrating data?

The best approach is gradual migration. Businesses can:

• Start by migrating less critical data first to identify inconsistencies.
• Use data validation tools to ensure accuracy before and after migration.
• Maintain a backup of the original database to prevent data loss.

Testing is just as necessary. Running parallel systems for a period allows businesses to compare real-time outputs and detect issues early.

? What strategies help ensure a smooth transition during migration?

As I already mentioned, the best approach is gradual migration. Another method is parallel deployment, where the old and new systems run simultaneously for a limited time. This allows teams to compare performance and user experience before making a switch.

For real-time applications, load balancing helps gradually shift traffic from the old system to the new one without sudden service disruptions.

? How does security factor into legacy system migration?

Many legacy systems lack modern security standards, making migration a good opportunity to eliminate vulnerabilities. However, the migration process introduces risks - data transfers, third-party integrations, and cloud migrations can expose security gaps.

To reduce risks, businesses should:

• Encrypt sensitive data during migration.
• Implement access controls to prevent unauthorized changes.
• Conduct security audits before deploying the new system.

Choosing a provider with built-in compliance tools simplifies security management for cloud migrations.

? What challenges do teams face when training employees on a new system?

Employees familiar with the legacy system may find the new workflows confusing at first, which can slow down adoption. For example, when switching from Redux to Zustand, I had to spend much more time than expected to explain and train the team not to write unnecessary code.

A structured training plan can help:

• Offering hands-on training sessions before the complete switch.
• Providing detailed but simple documentation for frequent tasks.
• Encouraging user feedback to refine the system based on practical usage.

This makes the transition smoother and helps employees feel more confident using the new system.

? What should businesses do if migration doesn’t go as planned?

There should always be a rollback plan if something doesn’t work as expected. This includes:

• Keeping backups of all critical data before making significant changes.
• Running a controlled test environment before full deployment.
• Having a dedicated troubleshooting team ready to address issues quickly.

Unexpected problems are common in migrations, but a well-prepared team can handle them without serious disruptions.

? What’s your advice for businesses planning a legacy migration?

Start by identifying what needs to be migrated - not everything from a legacy system must be transferred. Businesses should also map out all dependencies before starting, so they don’t run into unexpected technical issues.

A well-planned migration reduces risk, avoids unnecessary costs, and ensures a stable transition to modern technology. Taking the time to test, train employees, and have a backup plan will make the process smoother.

Migrating from a legacy system is a complex process, but with the right strategy, businesses can avoid unnecessary risks and ensure a smooth transition. Careful planning, step-by-step migration, and security-focused implementation make all the difference.

If your company is preparing for a legacy system migration, let’s discuss how to approach it efficiently and minimize disruptions. ?? Contact us today to plan a seamless transition to modern technology.