Legacy systems rarely disappear voluntarily in companies. They remain in place because no one can say for sure what will happen when they are shut down. Old ERP, MES or production systems often continue to run for years - not because of their functionality, but because of the data they contain.
After all, this is where historical orders, production data, quality records, audit trails or tax-relevant information are stored that must remain available. The problem is that many of these systems are expensive to operate, technically outdated, security-critical and almost impossible to maintain. At the same time, they prevent migrations, slow down modernization projects and create growing compliance risks.
This becomes a serious problem when it comes to SAP transformations, MES changes, cloud migrations or audits at the latest. Companies must then not only replace systems, but also ensure that historical data remains readable, audit-proof and auditable in the long term.
This article shows why legacy systems will become a risk for many companies in 2026, which errors are particularly common during system replacement and how historical data can be securely migrated and kept available in the long term - without having to continue operating the legacy system in the long term.
THE MOST IMPORTANT FACTS IN BRIEFLegacy systems are outdated ERP, MES or production systems that continue to be operated because historical data or business-critical processes depend on them. The problem is that many of these systems pose high operational, security and compliance risks. It becomes particularly critical during audits, migrations or ERP changes when historical data is no longer fully available or analyzable. Modern application retirement strategies make it possible to safely shut down legacy systems and still keep data available in an audit-proof manner in the long term. |
IN BRIEF
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Legacy systems are outdated software or IT systems that continue to be used productively even though they are technologically outdated. In companies, this often concerns ERP systems, MES platforms, production databases, archiving systems or individually developed applications that have grown over many years.
The actual problem is rarely the age of the software alone. A legacy system becomes critical when companies remain business-critical and dependent on it - even though maintenance, security, integration capability or data access are becoming increasingly difficult.
In practice, legacy systems often exist much longer than originally planned. Reasons for this include
This creates complex dependencies, particularly in industry. For example, an old MES system still contains production histories from previous years. The ERP archives tax-relevant business data. A machine control system stores quality parameters that are still required for traceability or product liability.
This is precisely why many systems are never completely switched off. Although companies modernize their operational IT landscape, they continue to operate old systems in parallel - simply because of data access.
The consequences are considerable:
There is also a technical risk: many legacy systems are based on technologies, databases or operating systems that are barely supported. Specialist knowledge is disappearing, spare parts are missing and security updates often no longer exist.
Legacy systems are therefore not only an IT problem, but also a strategic challenge for compliance, digitalization and risk management. Companies must decide which systems are still needed productively - and which data must remain available in the long term independently of the original system.
Many companies still regard legacy systems as a necessary evil. As long as the old ERP, MES or archive system is "still running", modernization is often postponed. However, this is precisely where the risk lies. Because costs, security problems and compliance requirements increase significantly with each passing year.
The situation in 2026 is particularly critical because many companies are facing several transformation projects at the same time:
Legacy systems are usually not designed for this. Many are based on outdated operating systems, databases that are no longer supported or proprietary interfaces. Security updates are lacking, integrations are becoming complicated and technical expertise is increasingly disappearing from companies.
At the same time, the data in these systems remains business-critical. This creates a dangerous contradiction:
The system should go - the data must stay.
The greatest risks arise in several areas at the same time:
| Risk | Typical problem | Impact |
|---|---|---|
| Cybersecurity | No security updates or outdated operating systems | Increased risk of attack |
| Compliance | Historical data not available for audit | Audit and fine risks |
| Operating costs | Old infrastructure and specialist knowledge required | High maintenance and license costs |
| Data access | Proprietary data formats | Historical information no longer readable |
| Digitization | Lack of interface capability | Delayed modernization |
| ERP/MES migrations | Historical data remains in the old system | Double operation for years |
This becomes particularly problematic with long-term retention obligations. Many companies have to keep production, quality or business data available for 10, 15 or even 30 years. However, operational systems are rarely designed for this.
This creates expensive parallel worlds:
New systems take over the ongoing processes, while old applications continue to operate solely because of historical data. Companies then continue to pay for hardware, databases, maintenance and specialist knowledge - even though the system is hardly used operationally.
There is also a compliance risk that is often underestimated: Historical data must not only be available, but must also remain audit-proof, traceable and machine analyzable. This is precisely what many legacy systems can no longer guarantee in the long term.
This is why legacy modernization is increasingly becoming a strategic issue. Companies must not only replace systems, but also ensure that historical data remains auditable in the long term - regardless of the original system.
The biggest problems with legacy systems are rarely reflected in the IT balance sheet. Many costs are incurred indirectly - through security risks, inefficient processes, audit costs or blocked modernization projects. This is precisely why companies often underestimate how expensive old systems have actually become.
The so-called "read-only operation" is particularly critical. Many ERP, MES or production systems are hardly used operationally, but continue to run exclusively because of historical data or legal retention obligations.
This leads to a costly situation:
The new system landscape is already productive - yet the old system remains in place.
The hidden costs arise in several areas at the same time:
| Cost factor | Typical problem | Business impact |
|---|---|---|
| Infrastructure costs | Old servers, databases and operating systems must continue to be operated | Ongoing operating and license costs |
| Specialized knowledge | Only a few employees still know the system | High dependency on individuals |
| Security risks | Lack of patches and outdated technologies | Cybersecurity and compliance risks |
| Audit effort | Historical data is difficult to access | High manual effort for audits |
| Parallel operation | New and old system run simultaneously | Double maintenance and support costs |
| Missing integrations | Legacy systems often do not support modern APIs | Delayed digitalization |
| Data migrations | Historical data remains in the legacy system | Long-term technical dependency |
| Vendor dependency | Proprietary data formats and software | Vendor lock-in |
Legacy systems become particularly expensive during ERP transformations or cloud migrations. Many companies invest millions in new platforms - but continue to operate old systems in parallel for years because historical data is still required.
There is also a risk that often only becomes apparent during an audit: Historical data must not only be stored, but also remain available in a readable, traceable and audit-proof manner. If data is only accessible via old applications, this creates a dangerous technical dependency.
In many companies, so-called "zombie systems" are growing as a result:
Applications that are hardly relevant from an operational point of view, but still cannot be switched off.
In the long term, such systems become blocked:
This is precisely why modern companies no longer view legacy systems as just an IT issue. They are a strategic cost, risk and compliance factor - especially where historical data must remain available in the long term.
The technical shutdown of a legacy system is usually not the real problem. It becomes critical when companies underestimate historical data, compliance requirements and long-term verification obligations. This is precisely why many modernization projects fail not because of the migration itself - but because of the data behind it.
Problems arise particularly frequently when system replacements are viewed exclusively as an IT project. In reality, however, they affect both at the same time:
The following errors occur particularly frequently in practice:
| Typical error | What happens in practice | The risk |
|---|---|---|
| Data migration without an archive strategy | Historical data remains in the old system | Permanent parallel operation |
| Backup confused with archiving | Data is technically available, but not auditable | Compliance risk |
| Only operational data is migrated | Historical audit and quality data is missing | Verification problems |
| Proprietary formats remain in place | Data remains tied to old software | Vendor lock-in |
| No data classification | Unclear retention and deletion obligations | GDPR and GoBD risks |
| Missing audit trails | Historical changes are not traceable | Revision problem |
| System is shut down too early | Data can no longer be read later | Loss of data |
| No departmental integration | Critical information is overlooked | Process interruptions |
The misconception that a complete data migration is always necessary is particularly problematic. In many cases, historical information does not need to be transferred to the new ERP or MES system. Instead, it is crucial that it remains available and auditable in the long term.
This is precisely where modern application retirement strategies come in:
Operational processes are migrated to new systems, while historical data is archived independently of the system and remains accessible.
This avoids many typical risks:
Another common mistake concerns data quality. Many legacy systems contain data structures that have grown over decades, duplicates or inconsistent information. Without early analysis, this can cause considerable problems during migrations or subsequent audit processes.
Successful legacy modernization therefore does not begin with shutting down the system, but with a clear strategy for:
Many companies believe that the problem of old systems is solved as soon as a backup exists. This is one of the most common misconceptions about legacy systems and application retirement.
A backup primarily protects against technical data loss - for example after hardware failures, cyber attacks or accidental deletion. However, this is not enough for long-term data availability, auditability or regulatory evidence.
The crucial difference:
A backup secures systems.
Archiving secures information.
This is particularly critical for legacy systems. This is because historical data often has to be stored for years to come:
Many classic backup solutions cannot achieve this.
The differences become particularly clear:
| Backup | Audit-proof archiving |
|---|---|
| Focus on restoring the system | Focus on long-term data availability |
| Designed for disaster recovery | Designed for audit and compliance requirements |
| Often proprietary formats | Long-term readable data storage |
| No guaranteed revision security | Unchangeable archiving |
| No structured audit access | Data can be analyzed selectively |
| Dependent on the original system | System-independent access |
| Short to medium-term storage | Long-term storage over years or decades |
This becomes particularly problematic when ERP, MES or production systems are shut down. Although backups of the databases often still exist, the information can often no longer be meaningfully interpreted or evaluated without the original application.
This poses a serious risk in the event of an audit:
The data exists technically - in practice it is no longer usable.
Added to this are regulatory requirements such as
These not only require data retention, but also:
This is precisely why a backup for legacy systems is not enough. Companies need an archive strategy that keeps historical data available independently of the original system - audit-proof, auditable and analyzable in the long term.
Only then is true application retirement possible:
The legacy system can be shut down without losing access to business-critical information.
Many companies have been trying for years to completely replace old ERP, MES or production systems - and fail not because of the technology, but because of the historical data. This is exactly where Application Retirement comes in.
The aim is not to migrate all information to new systems. Instead, operational processes are modernized while historical data from legacy systems is archived in an audit-proof manner and kept available in the long term.
This creates a decisive advantage:
The legacy system can be shut down without losing data or auditability.
Application Retirement thus reduces at the same time:
The typical process consists of several steps:
| Phase | Goal | Result |
|---|---|---|
| System analysis | Identify relevant data and dependencies | Transparency across the legacy landscape |
| Data classification | Define retention and compliance requirements | Clear archiving strategy |
| Data extraction | Transfer historical information from the legacy system | System-independent database |
| Audit-proof archiving | Ensure long-term readability and auditability | Compliance-compliant data storage |
| Shutting down the legacy system | Decommission infrastructure | Cost and risk reduction |
| Audit and user access | Keep historical data available | Permanent traceability |
The decoupling of data and application is particularly important. Historical information must not be dependent on the continued operation of old ERP or MES systems in the long term.
This is still the case in many companies today:
A system remains active - solely because of the data in it.
Modern application retirement strategies avoid this situation. Historical information is transferred to an independent archive in which it remains:
This means that even complex transformation projects can be significantly simplified. Companies can:
This is particularly relevant for long-term retention obligations. Production, quality or business data must often remain available for decades - significantly longer than the original software even exists.
Application Retirement therefore creates the basis for modern IT landscapes:
New systems take over operational processes, while historical data remains available in the long term regardless of this.
The biggest challenge with legacy systems does not end with the migration. The crucial question is whether historical data is still available years later in a complete, traceable and auditable form.
This is precisely where many companies fail. Although operational processes are successfully migrated to new ERP, MES or cloud systems, historical information remains in the old system or is only available as a database backup. In an emergency, it then becomes apparent that although important information exists in theory, it can no longer be used in practice.
This is particularly critical in the case of:
This is because historical data often has to remain available for much longer than the original software is in operation.
The requirements for long-term data availability are constantly increasing:
| Requirement | Why it is important |
|---|---|
| Audit security | Protection against manipulation and data loss |
| Long-term readability | Access independent of the original system |
| Auditability | Fast provision of historical evidence |
| Machine analyzability | Data must remain analyzable |
| Access control | Protection of sensitive information |
| Traceable history | Audit trails and change logs |
| Vendor independence | No vendor lock-in |
Many companies underestimate the importance of data formats. Historical information in proprietary ERP or MES structures often remains permanently tied to the original application. If this is switched off, a dangerous dependency is created:
The data exists - but no one can interpret it in a meaningful way anymore.
This is why modern archiving strategies rely on system-independent long-term archiving. Historical data is extracted from the legacy system and stored in an audit-proof structure that can still be accessed years later:
This enables companies to:
Many companies continue to operate legacy systems for years, even though they have long since been replaced operationally. The reason is almost always the same: historical data must remain available - for audits, traceability, compliance or legal retention obligations.
CHRONOS was developed precisely for this scenario. The platform makes it possible to transfer historical ERP, MES, production and archive data from legacy systems in an audit-proof manner and keep it available in the long term, independently of the original system.
This allows companies to shut down legacy systems without losing access to business-critical information.
☐ We know exactly which historical data from our legacy systems is still needed.
☐ Our historical ERP, MES or production data can be read independently of the original system.
☐ We could shut down a legacy system today without losing auditability.
☐ Historical data is archived in an audit-proof manner and can be analyzed automatically.
☐ Our backup strategy is clearly separated from the archiving strategy.
☐ We have defined retention and deletion periods for historical data.
☐ An auditor could retrieve historical evidence within a short time.
☐ Our legacy systems no longer cause permanent parallel operation.
☐ Historical data remains available even after ERP or SAP migrations.
☐ Our long-term archiving works independently of manufacturers and without vendor lock-in.
The more points that remain open, the greater the risk of legacy systems causing long-term costs, security problems and compliance risks. This becomes particularly critical during audits, cybersecurity incidents or system migrations - in other words, precisely when historical data needs to be available at short notice.
A legacy system is an outdated software or IT solution that continues to be used productively even though it is technologically obsolete. This often applies to ERP, MES, production or archiving systems that have grown over many years and still contain business-critical data.
In many companies, historical production, quality or business data is only available in the legacy system. This information is still required for audits, traceability, compliance or legal retention obligations. This is why systems often remain active for years in read-only mode.
Legacy systems significantly increase security, compliance and operational risks. Security updates, modern interfaces or manufacturer support are often missing. At the same time, high costs are incurred for infrastructure, maintenance and specialist knowledge. This becomes particularly critical when historical data is no longer available in an audit-proof manner.
No. A backup is primarily used for the technical recovery of systems. This is usually not sufficient for long-term auditability, compliance or historical evidence. Companies need audit-proof archiving that keeps data readable and traceable regardless of the original system.
Application retirement describes the controlled decommissioning of legacy systems. Historical data is extracted from the legacy system and archived in an audit-proof manner so that the original system can be shut down without losing important information.
Many ERP or MES migrations focus on operational processes. Historical data is therefore often left behind in the old system. Without a long-term archiving strategy, this results in parallel operation, compliance risks and technical dependencies on outdated software.
This depends on the industry and regulation. Typically, this concerns
Depending on the requirements, this data must remain available for 6, 10, 15 or even 30 years.
CHRONOS transfers historical data from ERP, MES and production systems into an audit-proof long-term architecture. This enables companies to switch off legacy systems and still keep historical information available in an auditable, readable and machine-readable form for the long term.