TypeError You provided an invalid object where a stream was expected You can provide an Observable Promise Array or Iterable

Question

I am trying to map from a service call but getting an error  Looked at subscribe is not defined in angular 2  and it said that in order to subscribe we need to return from inside the operators  I have return statements as well   Here s my code   checkLogin    Observable lt boolean gt        return this service getData            map              response   gt                    this data   response                                              this checkservice   true                  return true                             error   gt                       debugger                  this router navigate   newpage                     console log error                   return false                                   catch e   gt                return e                  Error log   TypeError  You provided an invalid object where a stream was expected  You can provide an Observable  Promise  Array  or Iterable

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In regard to the  You provided an invalid object where a stream was expected  You can provide an Observable  Promise  Array  or Iterable  error   This could happen if you import   Observable   from  rxjs  after  below  some module function whatever  which actually uses it   Solution  move this import above the import of that module

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I was forgetting to return the other observable in pipe switchMap   this dataService getPerson personId  pipe    switchMap person   gt           this dataService getCompany person companyId      return missing      return this dataService getCompany person companyId

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I was also facing the same issue when i was calling a method inside switchMap  apparently I found that if we use method inside switchMap it must return observable    i used pipe to return observable and map to perform operations inside pipe for an api call which i was doing inside method rather than subscribing to it

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In my case the error occurred only during e2e tests  It was caused by throwError in my AuthenticationInterceptor  I imported it from a wrong source because I used WebStorm s import feature  I am using RxJS 6 2  Wrong  import   throwError   from  rxjs internal observable throwError    Correct  import   throwError   from  rxjs    Here the full code of the interceptor  import   Injectable   from   angular core   import   HttpErrorResponse  HttpEvent  HttpHandler  HttpInterceptor  HttpRequest   from   angular common http   import   Observable  throwError   from  rxjs   import   catchError   from  rxjs operators     Injectable   export class AuthenticationInterceptor implements HttpInterceptor      intercept req  HttpRequest lt any gt   next  HttpHandler   Observable lt HttpEvent lt any gt  gt        const reqWithCredentials   req clone  withCredentials  true        return next handle reqWithCredentials        pipe          catchError error   gt              if  error status     401    error status     403                   handle error                       return throwError error

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I had the same issue caused by importing the internal version of  takeUntil  instead of the operators Change   import   takeUntil   from  rxjs internal operators takeUntil     to   import   takeUntil   from  rxjs operators     This happen also for other operators

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I ve had this error when there s been different RxJS-versions across projects  The internal checks in RxJS fails because there are several different Symbol observable  Eventually this function throws once called from a flattening operator like switchMap  Try importing symbol-observable in some entry point     main index ts import  symbol-observable

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You are returning an Observable where as your code returns just a boolean  So you need to use as below   map response   gt   lt boolean gt response json      If you are using another common service checkservice in your case  you can simply use   this service getData   subscribe data  gt console log data      This will make your checkLogin   function with return type as void   checkLogin   void        this service getData                map response   gt                                 this data   response                                                         this checkservice true                  subscribe data  gt         and you can use of this checkService to check your condition

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In my case I mistakely imported Action into my combineEpics  rather than Epic    Verify all the functions within combine Epics are epic funcitons

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I have been facing this issue when trying to authenticate a user using JSON Web Token  in my case it s related to authentication interceptor   Sending a request to authenticate a user doesn t have to provide a token since it doesn t exist yet   Check that your interceptor include this   if  req headers get  No-Auth       True               return next handle req clone       And that you provide   No-Auth   True   to your header s request like this      authenticateUser user   Observable lt any gt        const headers   new HttpHeaders   No-Auth   True         headers append  Content-Type    application json        return this httpClient post    this apiEndpoint  auth authenticate   user   headers  headers

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I wrote this because I arrive here searching for the same error  and this could be useful for someone in the future   I get the same error while trying to initialize a service variable from its constructor making a call to a remote API trough http get and  subscribe    After many tests without understanding what the problem was  i finally get it  My application had authentication and an HttpInterceptor  and i was trying to initialize the service calling a public API method using http get      without  No-Auth  headers  I added them like here  and problem solved for me   getData     var reqHeader   new HttpHeaders    Content-Type    application x-www-urlencoded   No-Auth   True          return this http get environment urlApi Literales    headers  reqHeader           What a headache

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Can be triggered by a stray comma     in an RxJS pipe      The compile won t catch this extra comma at the end  pipe first    map result   gt     event   completed   result  result       It becomes an  invisible  undefined operator which screws the whole pipe up  and leads to a very confusing error message - which in this case has nothing to do with my actual logic

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If your function is expecting to return a boolean  just do this    Import    import   of  Observable   from  rxjs   import   map  catchError   from  rxjs operators        Then   checkLogin    Observable lt boolean gt      return this service getData        pipe        map response   gt            this data   response          this checkservice   true          return true                  catchError error   gt            this router navigate   newpage             console log error           return of false

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In your example code  you have your map operator receiving two callbacks  when it should only be receiving one  You can move your error handling code to your catch callback   checkLogin   Observable lt boolean gt       return this service getData                           map response   gt                                this data   response                                                        this checkservice true                            return true                                                    catch error   gt                              this router navigate   newpage                               console log error                             return Observable throw error                                    You ll need to also import the catch and throw operators   import  rxjs add operator catch   import  rxjs add observable throw     EDIT   Note that by returning Observable throwin your catch handler  you won t actually capture the error - it will still surface to the console

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this error happened with me when i am using interceptor  you have to do this in your interceptor  return next handle request  map event   gt            if  event instanceof HttpResponse                       return event               catchError  error  HttpErrorResponse    gt            if  error status     401    error status     400                 some logic

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In my case in Angular-5  service file was not imported from which i was accessing the method and subscribing the data After importing service file it worked fine

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A hint for anyone experiencing this  This can happen when a switchMap doesn t receive an observable return value  like null   Simply add a default case  so it always returns an observable           switchMap  dateRange    gt              if  dateRange      Last 24 hours                 return  observable1                        if  dateRange      Last 7 Days                 return  observable2                        if  dateRange      Last 30 Days                 return  observable3                           This line will work for default cases           return  observableElse

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I m not sure if this will help anyone  but in my case further up my chain I was using distinctUntilChanged and an exception inside a function there was manifesting with this error message

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This error happened to me  angular 7     You provided an invalid object where a stream was expected  You can provide an Observable  Promise  Array  or Iterable    The error is actually self-explanatory  it says somewhere in the observable I pass the invalid object  In my case  there was lots of API call but all the calls were failing because of wrong server configuration  I tried to use map  switchMap  or other rxjs operator but the operators are getting undefined objects   So double-check your rxjs operator inputs

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I have the same exact error message while I was doing my unit test and throwing observable exception after mocking my services   I resolved it by passing exact function and format inside Observable throw   Actual code which calls the service and subscribe to get data  notice that catch to handle the 400 error        this search event  catch  e  Response    gt            if  e status     400              console log e json   message             else if  e url              console log  HTTP Error      e status         e statusText               URL      e url   Info      e json   message                       finally      gt            this loading   false           subscribe  bData    gt            this data   bData              The code inside the service    search         return this someService getData request          do  r    gt              this someService defaultHeaders delete  skipAlert              return r                    map  r    gt              return r businessObjectDataElements length  amp  amp  r businessObjectDataElements    null                    Unit Testing  I have mocked the SomeService and returning observable data and its fine as it have all the required methods inside it    someServiceApi   fixture debugElement injector get SomeService    spyOn someServiceApi   getData   and returnValue Observable of         The above code is okey but when when I was trying to test the catch error condition by passing Observable throw     it was showing me the error as it was expecting Response type return from the service   So below service mocking return was giving me that error   someServiceApi getData    and returnValue Observable throw new Response  status  400  body      message   not found error         So I Corrected it by replicating the exact expected function in my return object rather passing a Response type value   someServiceApi getData    and returnValue Observable throw  status  400  json       gt    return  message   not found error     body            see  json       gt    return  message   not found error     inside return value

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You will get the following error message too when you provide undefined or so to an operator which expects an Observable  eg  takeUntil  TypeError  You provided an invalid object where a stream was expected  You can provide an Observable  Promise  Array  or Iterable

[angular] TypeError: You provided an invalid object where a stream was expected. You can provide an Observable, Promise, Array, or Iterable

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