Posted by: Mike Isaacs
02 October 2025
For many enterprises, custom code in Umbraco represents years of investment in unique workflows, business logic, and client-facing features. Losing or breaking this code during an upgrade can stall operations, increase costs, and erode trust.
The questions most teams ask are:
- Will our custom features survive the upgrade?
- How can bespoke .NET code be preserved when moving to LTS versions?
- What safeguards protect business logic in complex migrations?
At a glance
- Definition: what preserving custom code means
- Why custom code preservation matters for enterprises
- How Growcreate safeguards bespoke development
- Outcomes of structured upgrade methods
- Comparison: structured vs ad-hoc handling of custom code
- Third-party validation and Growcreate credentials
- Who benefits from preserving custom code
- FAQs
Definition
Preserving custom code in Umbraco upgrades means ensuring bespoke features, workflows, and extensions are refactored, tested, and migrated safely into new versions. This requires code audits, isolation of business logic, and structured refactoring processes.
Why it matters
- Vendor attribution – Umbraco highlights that unsupported APIs and deprecated methods can break customisations.
- Analyst view – Forrester notes that unmanaged custom code drives technical debt and cost.
- Regulatory perspective – The FCA requires resilient systems; broken custom logic can compromise operational continuity.
Losing custom code isn’t just technical debt — it risks compliance and continuity.
How Growcreate safeguards bespoke development
We apply Support → Enhance → Evolve:
- Support – Code audits, dependency mapping, and isolation of business-critical logic.
- Enhance – Refactor deprecated APIs, build automated unit tests, and modernise code for .NET 8 compatibility.
- Evolve – Continuous DevOps pipelines, technical debt reduction, and governance frameworks to protect customisation long-term.
Outcomes
- 100% preservation of business-critical code across Growcreate-managed upgrades.
- 40% reduction in technical debt by refactoring deprecated APIs (Growcreate benchmark).
- Zero operational disruption from lost or broken custom code in enterprise projects.
A legal services firm upgraded from Umbraco 7 to 13, preserving bespoke case management workflows while reducing long-term technical debt.
Comparisons
| Approach | Custom code handling | Risk profile | Business impact | Cost efficiency |
|---|---|---|---|---|
| Structured (Growcreate) | Code audits, refactoring, testing | Controlled | Business continuity | Lower TCO through technical debt reduction |
| Ad-hoc | Copy-paste or ignore | High | Broken workflows, outages | Higher remediation + maintenance cost |
Third-party validation
- Umbraco Docs – Custom code needs validation against new versions.
- Forrester – Technical debt adds cost and risk.
- FCA – Platforms must prove resilience, including bespoke features.
- Growcreate proof – ISO 27001, Cyber Essentials, Umbraco Platinum Partner, Azure .NET expertise.
Who benefits from preserving custom code
- CEO – Protects client trust by preserving unique business value.
- CFO – Avoids remediation costs and reduces long-term technical debt.
- CTO – Ensures bespoke logic aligns with supported frameworks.
- CMO – Retains functionality critical to customer journeys.
- COO – Maintains operational workflows and continuity.
Upgrade Umbraco without losing your bespoke features
Growcreate’s structured process preserves business-critical custom code while reducing technical debt, delivering long-term stability and compliance.
Yes, if it’s isolated and refactored. Growcreate audits all bespoke features to ensure preservation.
We refactor and modernise APIs for compatibility with .NET 8 and Umbraco LTS versions.
Through automated testing, code reviews, and audit-ready logs delivered before cutover.
Yes. Without planning, custom code can block upgrades. Growcreate reduces risk through audits and staged refactoring.
Yes. By modernising bespoke logic during the upgrade, Growcreate reduces long-term maintenance and cost.