From LTC 0.21.4 to Mooncoin: A Migration Story of Bringing a Legacy Chain Back to a Modern Baseline

This post documents how we migrated Mooncoin to a Litecoin Core 0.21.4 baseline after years of limited maintenance.
The goal was not to “restart” the chain, but to deliver a maintainable, reproducible, and releasable upgrade while preserving chain continuity.

Why this migration was necessary

Mooncoin had gone through a long period without sustained maintenance.
In practice, the legacy codebase faced several issues:

• Outdated baseline with high maintenance overhead
• Poor compatibility with modern systems and toolchains
• Non-reproducible builds across machines
• Aging wallet/node operational experience

So the migration goals were:

1. Move the engineering baseline to LTC 0.21.4
2. Preserve mainnet history and consensus continuity
3. Restore and validate wallet usability
4. Establish practical Linux / WSL / Windows build workflows

Consensus boundary: upgrade is not a reset

The most important principle was clear boundaries:

• No historical block rewrite
• No rollback of existing chain state
• No chain-swap style migration

Taproot / MWEB code paths remain present, but are not activated by default under current mainnet policy.
In other words: chain consistency first; governance and activation should be coordinated and height-based.

Engineering reality: where most time went

The hardest part was not changing one or two parameters, but making the build and release pipeline reproducible.

1) Choosing the Windows build path

The most stable path for this code line is:
WSL/Linux + depends cross-compilation.

Practical conclusions:

• depends can be built in parallel (-j$(nproc))
• Top-level project build is more stable with single-thread (make -j1) to avoid linker race failures

This was later documented so future maintainers do not repeat the same build traps.

2) “Builds successfully” is not the same as “release-ready”

We repeatedly hit real-world issues such as:

• Missing Qt / qrencode / libsodium link targets
• Berkeley DB version constraints
• Random undefined reference errors under parallel build
• PATH/toolchain contamination causing unstable results

Final strategy: lock down reproducibility first, optimize speed second.

Peer discovery problem: from “0 connections” to a usable bootstrap

The biggest end-user issue after migration was:
on some environments, first startup could show connections = 0.

We handled this in two stages:

1. Strengthen built-in seed / fixed-seed behavior
2. Ship a temporary mooncoin.conf bootstrap workaround in release notes

In weak network conditions, manual bootstrap significantly improved first-connect success.
Availability first, DNS seeder improvement next.

Wallet validation: more than compile logs

We performed real chain-level validation, not just compile checks:

• New wallet startup and sync work
• Transactions are broadcast and confirmed
• Address compatibility scenarios were tested (including bech32 flows)

For community trust, “can sync / can receive / can send” matters more than any roadmap statement.

Release engineering: more than a single exe

Release assets were structured with verification in mind:

• Windows package
• Linux node package (no-wallet build)
• SHA256SUMS checksums
• Verification commands in release notes

We also prepared split-chain snapshot assets as an optional sync accelerator, with clear warnings:

• Not a wallet backup
• No private keys included
• Node still verifies and continues syncing to network tip

What this migration actually delivered

This is more than a version bump:

• Better maintainability on a modern baseline
• More reproducible build workflow across machines
• Clearer node operation and release procedures
• Easier community collaboration through reproducible bug reports/fixes

For a long-undermaintained project, this is the foundation for sustainability.

What is next

Migration completion is not the end. Next priorities include:

• Better cold-start peer discovery (DNS seeder strategy)
• Broader cross-platform test coverage
• Community feedback driven patch releases
• Governance-led feature activation planning under chain-consistency constraints

Acknowledgment

This migration was not one “big trick”; it was many rounds of debugging, verification, and regression checks.
Thanks to everyone still running nodes, testing builds, and supporting Mooncoin.

If you are testing this version, useful feedback includes:

• OS and version
• Startup/sync stability
• Receive/send behavior
• Error logs and reproduction steps

That feedback directly improves the next release quality.