My Dawn theme version is 12.
I want to upgrade to dawn 15 but I’m afraid of loosing all the custom codes.
Is there any easy way to make the codes apply to the new version?
Topic summary
Main issue: Upgrading Shopify’s Dawn theme from version 12 to 15.0.2 without losing custom code.
- Consensus: There is currently no automatic tool or quick method to migrate customizations between Dawn versions. Custom code must be manually re-implemented in the new theme.
- Precaution: Back up the existing theme before updating. An image was shared showing the backup step, but it’s not essential to understand the guidance.
- Best practices: Maintain detailed documentation of every customization (what changed, where, and why). This significantly shortens re-implementation time when upgrading.
- Experience shared: With excellent documentation, re-customizing a full site after an update can be completed in about a day; without it, it may take many hours.
- Status/outcome: No automated solution; recommended approach is backup + thorough documentation + manual re-application of changes. The original poster remains frustrated and hopes for a future migration option.
Yes I know, I always make sure to have a backup but that still doesn’t answer my question.
Is there a quick way to transfer the codes or do I now have to re-implement all the codes in the latest them?
As far as I know, up to now, there is no solution or tool to support that other than having to redo it in the new version. 
Now I need to do this and waste a lot of hours. 
I really hope one day this option will be available.
So I have done this change a couple of times with different theme updates. The best way so far personally was to have excellent documentation of each custom code. What would take me quite a long time, would now take me a day to customise a whole website. Hope it helps.