FirebaseError, Error: Provided secretKey is invalid

I am using Firebase to run my backend.

However when I run it with NODE_ENV=debug firebase emulators:start --inspect-functions, it says

  emulators: Starting emulators: auth, functions, storage
⚠  functions: You are running the Functions emulator in debug mode (port=9229). This means that functions will execute in sequence rather than in parallel.
⚠  functions: The following emulators are not running, calls to these services from the Functions emulator will affect production: firestore, database, hosting, pubsub
⚠  functions: Unable to fetch project Admin SDK configuration, Admin SDK behavior in Cloud Functions emulator may be incorrect.
i  ui: Emulator UI logging to ui-debug.log
i  functions: Watching "/home/ktk/code/js/sol/functions/functions" for Cloud Functions...
✔  functions: Using node@18 from host.
i  functions: Loaded environment variables from .env.
⬢  functions: Failed to load function definition from source: FirebaseError: Failed to load function definition from source: Failed to generate manifest from function source: Error: provided secretKey is invalid

The logs:

[debug] [2023-04-17T17:52:25.003Z] Got response from /__/functions.yaml Failed to generate manifest from function source: Error: provided secretKey is invalid
[debug] [2023-04-17T17:52:25.006Z] Failed to parse functions.yamlincomplete explicit mapping pair; a key node is missed; or followed by a non-tabulated empty line at line 1, column 56:
     ... fest from function source: Error: provided secretKey is invalid
                                         ^ {"name":"YAMLException","reason":"incomplete explicit mapping pair; a key node is missed; or followed by a non-tabulated empty line","mark":{"name":null,"buffer":"Failed to generate manifest from function source: Error: provided secretKey is invalidnu0000","position":55,"line":0,"column":55},"message":"incomplete explicit mapping pair; a key node is missed; or followed by a non-tabulated empty line at line 1, column 56:n     ... fest from function source: Error: provided secretKey is invalidn                                         ^"}
[debug] [2023-04-17T17:52:25.017Z] shutdown requested via /__/quitquitquit