Firebase cloud function exits with code 16 what is error code 16 and where can I find more info?

Question

one of my cloud functions on firebase exits with code 16 as an error.

I tried to google and find out what that code is but no luck at all.

Error: Process exited with code 16     at process.on.code (/srv/node_modules/@google-cloud/functions-framework/build/src/invoker.js:393:29)     at process.emit (events.js:189:13)     at process.EventEmitter.emit (domain.js:441:20)     at process.exit (internal/process/per_thread.js:168:15)     at logAndSendError (/srv/node_modules/@google-cloud/functions-framework/build/src/invoker.js:184:9)     at process.on.err (/srv/node_modules/@google-cloud/functions-framework/build/src/invoker.js:390:13)     at process.emit (events.js:189:13)     at process.EventEmitter.emit (domain.js:441:20)     at emitPromiseRejectionWarnings (internal/process/promises.js:119:20)     at process._tickCallback (internal/process/next_tick.js:69:34)  

Where can I find those error codes reported so I can understand why my function exits?

Answer 1

Apparently and after investigation, the error means something like: Headers already sent.

I had somewhere in my code a response.send() with headers and then, later on, I was sending another response.

Would be great if the Firebase team could elaborate with these issues and provide some documentation instead of leaving us blindfolded (to my understanding)

Answer 2

An improperly terminated cloud function is the likely cause.

Here's what the firebase docs say:

• Resolve functions that perform asynchronous processing (also known as "background functions") by returning a JavaScript promise.

• Terminate HTTP functions with res.redirect(), res.send(), or res.end().

• Terminate a synchronous function with a return; statement.

In short, watch out for floating promises and/or multiple calls to res or response.

I've also seen the Process exited with code 16 occur in tandem with:

Error: Could not load the default credentials. Browse to https://cloud.google.com/docs/authentication/getting-started for more information.     at GoogleAuth.getApplicationDefaultAsync (/srv/functions/node_modules/google-auth-library/build/src/auth/googleauth.js:161:19)     at process._tickCallback (internal/process/next_tick.js:68:7)