SharedPreferences error in Flutter

Question

I was using shared_preferences plugin in my Flutter application. From one moment (probably after Flutter upgrade), it started to throw an exception:

E/flutter (27778): [ERROR:topaz/lib/tonic/logging/dart_error.cc(16)] Unhandled exception:
E/flutter (27778): type '_InternalLinkedHashMap' is not a subtype of type 'Map<String, Object>' where
E/flutter (27778):   _InternalLinkedHashMap is from dart:collection
E/flutter (27778):   Map is from dart:core
E/flutter (27778):   String is from dart:core
E/flutter (27778):   Object is from dart:core
E/flutter (27778): 
E/flutter (27778): #0      SharedPreferences.getInstance (package:shared_preferences/shared_preferences.dart)
E/flutter (27778): <asynchronous suspension>
E/flutter (27778): #1      loadFirstUse (**path**/lib/main.dart:29:53)
E/flutter (27778): <asynchronous suspension>
E/flutter (27778): #2      main (**path**/lib/main.dart:17:9)
E/flutter (27778): <asynchronous suspension>
E/flutter (27778): #3      _startIsolate.<anonymous closure> (dart:isolate/runtime/libisolate_patch.dart:279:19)
E/flutter (27778): #4      _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:165:12)

It happens when I simple try to create instance of SharedPreferences:

SharedPreferences prefs = await SharedPreferences.getInstance();

I was trying to find root of the problem, but was unable to find it. Thank you for any help.

EDIT: I am using shared_preferences: "^0.4.0"

Bellyband

github.com/flutter/flutter/issues/10872 – Web

I had this problem using the Dart 2.0 preview. I guess that should be fixed using shared_preferences 0.4.0, which version are you using? – Selfcongratulation

@Selfcongratulation I am using shared_preferences: "^0.4.0" – Bellyband

@NileshRathod Tried to change to "0.2.4" as you suggested, no difference – Bellyband

No idea if this will help, but perhaps you could try doing flutter clean as well as pub cache repair to see if you can shake things out – Persona

pub cache repair shouldn't be necessary. I need flutter clean frequently though to ensure changes take effect. – Nereus

Tried to pub cache repair and flutter clean, nothing helped – Bellyband

Answer 1

I've tried shared_preferences: "0.2.4" and other versions suggested above without any success. Finally got it to work after changing flutter channel from dev to beta:

flutter channel beta

At least this fixes this problem for now and just wait for a fix for the shared_preferences plugin on the dev channel.

Dissociate

I tried this but get the message git: Already on 'beta' and I am already using 0.2.4 Still get the same error. – Abdu

Answer 2

I solved this using the following workaround:

Future<SharedPreferences> prefs = SharedPreferences.getInstance();
prefs.then(
  (pref)
  {
    //call functions like pref.getInt(), etc. here
  }
);

Inflation

Answer 3

To debug this, use the following:

Future<SharedPreferences> _sprefs = SharedPreferences.getInstance();
_sprefs.then((prefs) {
  // ...
}, 
onError: (error) {
  print("SharedPreferences ERROR = $error");   
});

In my case the error was that I wanted to call await SharedPreferences.getInstance() before I called runApp(), so that solution the error message gave me was to order my code as follows:

First:

WidgetsFlutterBinding.ensureInitialized();

Afterwards:

SharedPreferences prefs = await SharedPreferences.getInstance();

Finally:

runApp(...);

Eigenvalue

Answer 4

I fixed it by changing to shared_preferences: "0.3.3". There is a good chance this breaks again.

Mackenziemackerel

I still get the same error after changing to 0.3.3 – Abdu

@Guus, yeah, not exactly sure why the fix worked for us. We ended up switching our entire state management to Redux. If you want to continue using shared_preferences, maybe try some other version numbers to see if they fix the issue. Sorry I can't give you a better answer. – Mackenziemackerel

Answer 5

you need to use Future like this

Future<SharedPreferences> _sprefs = SharedPreferences.getInstance();

Nickolai

Need a more complete example. Can you show code to get a preference, please? – Scotland

Answer 6

I remove packages one by one, and found that it was caused by flutter_barcode_scanner. I upgraded it to version 2.0.0 and it solved my problem.

Mauro

Answer 7

It was working fine earlier but now I am getting invalid format exception while calling SharedPreferences.getInstance();

and for solution I tried everything but nothing work.so at last I create new project and paste all my previous code. and that's finally solve the problem

Whitening