Error when using `nApi` preview feature flag: `Can't modify an already connected engine.`

Bug description

Hi. A while ago I made this issue about nApi. And because I couldn’t use it, I removed nApi from my project. But I started using it again a couple of days ago.

Since I started using it again. I haven’t had a problem with production and no errors like the issue above. But I started getting a new error in development on my own PC (windows 10).

Error:

(node:5568) UnhandledPromiseRejectionWarning: 
Error: {
"is_panic":false,
"message":"Can't modify an already connected engine.",
"backtrace":"   0: napi_register_module_v1\n  
 1: napi_register_module_v1\n   2: napi_register_module_v1\n   3: <unknown>\n   4: <unknown>\n   5: <unknown>\n   6: <unknown>\n   7: <unknown>\n   8: <unknown>\n   9: napi_register_module_v1\n  10: napi_register_module_v1\n  11: napi_register_module_v1\n  12: napi_register_module_v1\n  13: napi_register_module_v1\n  14: napi_register_module_v1\n  15: napi_register_module_v1\n  16: napi_register_module_v1\n  17: napi_register_module_v1\n  18: napi_register_module_v1\n  19: napi_register_module_v1\n  20: BaseThreadInitThunk\n  21: RtlUserThreadStart\n"}

I use nodemon (v 2.0.9) with express (v 4.17.1).

My main database is Postgress (which I use Prisma for), and redis with node-redis (v 3.1.2) which runs in a windows Ubuntu (WSL) terminal.

I use the integrated git bash for vscode as my main terminal (where I run nodemon).

How to reproduce

1. open an express project that uses postgress Prisma and nApi
2. open git bash in vscode + ubuntu (WSL) terminal that runs redis with node-redis
3. run the project with nodemon
4. stop nodemon using CTRL+C
5. start it immediately after
6. see error

Expected behavior

Connect to the already existing engine instead of throwing this error.

Prisma information

generator client {
  provider        = "prisma-client-js"
  previewFeatures = ["selectRelationCount", "nApi"]
}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

...

Environment & setup

• OS: Windows 10 Pro version 21H1
• Database: PostgreSQL 13
• Node.js version 14.17.2
• Nodemon version 2.0.9
• Git bash version 2.32.0.2

Prisma Version

prisma               : 2.29.0
@prisma/client       : 2.29.0
Current platform     : windows
Query Engine         : query-engine 1be4cd60b89afa04b192acb1ef47758a39810f3a (at node_modules\@prisma\engines\query-engine-windows.exe)
Migration Engine     : migration-engine-cli 1be4cd60b89afa04b192acb1ef47758a39810f3a (at node_modules\@prisma\engines\migration-engine-windows.exe)
Introspection Engine : introspection-core 1be4cd60b89afa04b192acb1ef47758a39810f3a (at node_modules\@prisma\engines\introspection-engine-windows.exe)
Format Binary        : prisma-fmt 1be4cd60b89afa04b192acb1ef47758a39810f3a (at node_modules\@prisma\engines\prisma-fmt-windows.exe)
Default Engines Hash : 1be4cd60b89afa04b192acb1ef47758a39810f3a
Studio               : 0.419.0
Preview Features     : selectRelationCount, nApi

[mostafa7904]

I haven’t personally seen any reoccurrence of this either. I’ll reopen another issue if it happens again.

[janpio]

That’s fine, thanks for letting us know. We will see if we can get this fixed (or worked around).