nextjs - 💡(How to fix) Fix HRM broken with React Server Component in dynamic App route. [1 comments, 1 participants]

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vercel/next.js#84198Fetched 2026-04-08 02:20:17
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Code Example

OS: Windows
Node: v20.18.0
See also package.json.
RAW_BUFFERClick to expand / collapse

Link to the code that reproduces this issue

https://github.com/shinobijs/nextjs-sample/tree/hrm-reproduce

To Reproduce

  1. Start the application with npm run dev.
  2. Open home page in the browser.
  3. Refresh the page and the server log shows no side-effects.
  4. Open the dynamic route e..g. /123456.
  5. Refresh the page and the server log shows side-effect.

Current vs. Expected behavior

It would be expected that reloading a dynamic route page that uses a React Server Function has no undesired side-effects in the development environment.

Issues:

  1. Cascading effect of hot re-loading modules that are already loaded.
  2. Global variables are not recognized during hot re-loading a module.

The issues only happen from dynamic routes in the App, other routes behave as expected. The issues are visualized on the server with log statement.

In an actual application the above can have major side-effects; e.g. Mongoose models, Redis connections, caching and classes (with static variables).

Provide environment information

OS: Windows
Node: v20.18.0
See also package.json.

Which area(s) are affected? (Select all that apply)

Server Actions, Dynamic Routes

Which stage(s) are affected? (Select all that apply)

next dev (local)

Additional context

The unpredictable behavior makes singleton patterns useless, has a cascading effect of reloading many Mongoose models with references, and deletes database connections.(e.g. MonoDB, Redis).

extent analysis

TL;DR

  • Refactor the code to avoid using global variables and singleton patterns in dynamic routes to prevent undesired side-effects during hot reloading in the development environment.

Guidance

  • Identify and refactor modules that are causing cascading effects during hot reloading, focusing on those using Mongoose models, Redis connections, and caching.
  • Review the usage of React Server Functions in dynamic routes to ensure they are properly handling hot reloading without introducing side-effects.
  • Consider implementing a mechanism to detect and handle hot reloading of modules, potentially using a library or custom solution to manage global state and connections.
  • Investigate the possibility of using a development environment configuration that disables or mitigates the effects of hot reloading on dynamic routes.

Example

No specific code example can be provided without modifying the original codebase, but reviewing the nextjs-sample repository and focusing on the dynamic route handling and module imports may help identify the root cause.

Notes

The provided information suggests that the issue is specific to the development environment and dynamic routes, and refactoring the code to avoid global variables and singleton patterns may help mitigate the problem. However, without further investigation and testing, it is uncertain whether this will fully resolve the issue.

Recommendation

  • Apply workaround: Refactor the code to avoid using global variables and singleton patterns in dynamic routes, as this is likely to reduce the occurrence of undesired side-effects during hot reloading.

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nextjs - 💡(How to fix) Fix HRM broken with React Server Component in dynamic App route. [1 comments, 1 participants]