This is my first time in the site, so sorry for bad question post, so, my app was working normally, no problems, today when I tried to run npm run dev (I didn't change anything just run it) I got this weird error, that even the terminal wasn't enough to fit it , anyone have any idea ?

./node_modules/next/dist/client/ponents/router-reducer/reducers/prune-prefetch-cache.js
There are multiple modules with names that only differ in casing.
This can lead to unexpected behavior when piling on a filesystem with other case-semantic.
Use equal casing. Compare these module identifiers:
* javascript/auto|E:\Development\gero-admin\node_modules\next\dist\piled\@next\react-refresh-utils\dist\loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-flight-client-module-loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-swc-loader.js??ruleSet[1].rules[13].oneOf[4].use[2]!E:\Development\gero-admin\node_modules\next\dist\client\ponents\router-reducer\reducers\prune-prefetch-cache.js|app-pages-browser
    Used by 3 module(s), i. e.
    javascript/auto|E:\Development\gero-admin\node_modules\next\dist\piled\@next\react-refresh-utils\dist\loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-flight-client-module-loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-swc-loader.js??ruleSet[1].rules[13].oneOf[4].use[2]!E:\Development\gero-admin\node_modules\next\dist\client\ponents\router-reducer\reducers\navigate-reducer.js|app-pages-browser
* javascript/auto|E:\Development\gero-admin\node_modules\next\dist\piled\@next\react-refresh-utils\dist\loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-flight-client-module-loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-swc-loader.js??ruleSet[1].rules[13].oneOf[4].use[2]!E:\development\gero-admin\node_modules\next\dist\client\ponents\router-reducer\reducers\prune-prefetch-cache.js|app-pages-browser
    Used by 3 module(s), i. e.
    javascript/auto|E:\Development\gero-admin\node_modules\next\dist\piled\@next\react-refresh-utils\dist\loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-flight-client-module-loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-swc-loader.js??ruleSet[1].rules[13].oneOf[4].use[2]!E:\development\gero-admin\node_modules\next\dist\client\ponents\router-reducer\reducers\navigate-reducer.js|app-pages-browser

Import trace for requested module:
./node_modules/next/dist/client/ponents/router-reducer/reducers/prefetch-reducer.js
./node_modules/next/dist/client/ponents/router-reducer/router-reducer.js
./node_modules/next/dist/shared/lib/router/action-queue.js
./node_modules/next/dist/client/ponents/use-reducer-with-devtools.js
./node_modules/next/dist/client/ponents/app-router.js

This error goes over and over again.

I cleared browser history and cache, deleted the next. folder, but nothing happens.

This is my first time in the site, so sorry for bad question post, so, my app was working normally, no problems, today when I tried to run npm run dev (I didn't change anything just run it) I got this weird error, that even the terminal wasn't enough to fit it , anyone have any idea ?

./node_modules/next/dist/client/ponents/router-reducer/reducers/prune-prefetch-cache.js
There are multiple modules with names that only differ in casing.
This can lead to unexpected behavior when piling on a filesystem with other case-semantic.
Use equal casing. Compare these module identifiers:
* javascript/auto|E:\Development\gero-admin\node_modules\next\dist\piled\@next\react-refresh-utils\dist\loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-flight-client-module-loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-swc-loader.js??ruleSet[1].rules[13].oneOf[4].use[2]!E:\Development\gero-admin\node_modules\next\dist\client\ponents\router-reducer\reducers\prune-prefetch-cache.js|app-pages-browser
    Used by 3 module(s), i. e.
    javascript/auto|E:\Development\gero-admin\node_modules\next\dist\piled\@next\react-refresh-utils\dist\loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-flight-client-module-loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-swc-loader.js??ruleSet[1].rules[13].oneOf[4].use[2]!E:\Development\gero-admin\node_modules\next\dist\client\ponents\router-reducer\reducers\navigate-reducer.js|app-pages-browser
* javascript/auto|E:\Development\gero-admin\node_modules\next\dist\piled\@next\react-refresh-utils\dist\loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-flight-client-module-loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-swc-loader.js??ruleSet[1].rules[13].oneOf[4].use[2]!E:\development\gero-admin\node_modules\next\dist\client\ponents\router-reducer\reducers\prune-prefetch-cache.js|app-pages-browser
    Used by 3 module(s), i. e.
    javascript/auto|E:\Development\gero-admin\node_modules\next\dist\piled\@next\react-refresh-utils\dist\loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-flight-client-module-loader.js!E:\Development\gero-admin\node_modules\next\dist\build\webpack\loaders\next-swc-loader.js??ruleSet[1].rules[13].oneOf[4].use[2]!E:\development\gero-admin\node_modules\next\dist\client\ponents\router-reducer\reducers\navigate-reducer.js|app-pages-browser

Import trace for requested module:
./node_modules/next/dist/client/ponents/router-reducer/reducers/prefetch-reducer.js
./node_modules/next/dist/client/ponents/router-reducer/router-reducer.js
./node_modules/next/dist/shared/lib/router/action-queue.js
./node_modules/next/dist/client/ponents/use-reducer-with-devtools.js
./node_modules/next/dist/client/ponents/app-router.js

This error goes over and over again.

I cleared browser history and cache, deleted the next. folder, but nothing happens.

• javascript
• reactjs
• node.js
• typescript
• next.js

2 Answers 2

This issue often occurs when there's a mismatch between file or directory names in your imports and the actual file system. For example, importing ./MyModule and ./mymodule could cause such conflicts.

To resolve this, ensure your project's file and directory names match your import statements and the naming conventions are consistent throughout the project. Delete the node_modules and the build folders, then run npm install again to rebuild the project.

Was having this on Windows 10 and Next.js 14.2.15 and getting console errors that said There are multiple modules with names that only differ in casing. VS code defaults to Powershell so I switched from using VSCode integrated terminal to cmd in another window and that fixed it.