diff --git a/android/src/main/java/com/launchdarkly/reactnative/LaunchdarklyReactNativeClientModule.java b/android/src/main/java/com/launchdarkly/reactnative/LaunchdarklyReactNativeClientModule.java
index 9bf022c..cabce69 100644
--- a/android/src/main/java/com/launchdarkly/reactnative/LaunchdarklyReactNativeClientModule.java
+++ b/android/src/main/java/com/launchdarkly/reactnative/LaunchdarklyReactNativeClientModule.java
@@ -196,16 +196,11 @@ public void configureWithTimeout(ReadableMap config, ReadableMap user, Integer t
 
     private void internalConfigure(ReadableMap config, ReadableMap user, final Integer timeout, final Promise promise) {
         try {
-            if (LDClient.get() != null) {
-                promise.reject(ERROR_INIT, "Client was already initialized");
-                return;
-            }
-        } catch (LaunchDarklyException e) {
-            //This exception indicates that the SDK has not been initialized yet
-        } catch (Exception e) {
-            Timber.w(e);
-            promise.reject(ERROR_INIT, e);
+            LDClient.get();
+            promise.reject(ERROR_INIT, "Client was already initialized");
             return;
+        } catch (LaunchDarklyException e) {
+            // This exception indicates that the SDK has not been initialized yet
         }
 
         final LDConfig.Builder ldConfigBuilder = configBuild(config);
@@ -236,7 +231,11 @@ public void run() {
                     if (timeout != null) {
                         LDClient.init(application, ldConfigBuilder.build(), userBuilder.build(), timeout);
                     } else {
-                        LDClient.init(application, ldConfigBuilder.build(), userBuilder.build());
+                        try {
+                            LDClient.init(application, ldConfigBuilder.build(), userBuilder.build()).get();
+                        } catch (ExecutionException | InterruptedException e) {
+                            Timber.e(e, "Exception during Client initialization");
+                        }
                     }
                     promise.resolve(null);
                 }
@@ -605,13 +604,9 @@ private void resolveJsonElementDetail(Promise promise, EvaluationDetail<JsonElem
     @ReactMethod
     public void allFlags(String environment, Promise promise) {
         try {
-            if (!LDClient.get().isInitialized()) {
-                promise.reject(ERROR_INIT, "Client is not yet initialized");
-                return;
-            }
-        } catch (Exception e) {
-            Timber.w(e);
-            promise.reject(ERROR_INIT, "Client is not yet initialized");
+            LDClient.get();
+        } catch (LaunchDarklyException e) {
+            promise.reject(ERROR_INIT, "SDK has been not configured");
             return;
         }
         
@@ -661,7 +656,11 @@ public void allFlags(String environment, Promise promise) {
                 }
             }
             promise.resolve(response);
+        } catch (LaunchDarklyException e) {
+            // Since we confirmed the SDK has been configured, this exception should only be thrown if the env doesn't exist
+            promise.reject(ERROR_UNKNOWN, "SDK not configured with requested environment");
         } catch (Exception e) {
+            promise.reject(ERROR_UNKNOWN, "Unknown exception in allFlags");
             Timber.w(e);
         }
     }
diff --git a/index.js b/index.js
index 9dcea3d..1681161 100644
--- a/index.js
+++ b/index.js
@@ -19,22 +19,27 @@ export default class LDClient {
   }
 
   configure(config, user, timeout) {
-    if (this.isInitialized() == true) {
-      Promise.reject('LaunchDarkly SDK already initialized');
-    }
-    const configWithOverriddenDefaults = Object.assign({
-      backgroundPollingIntervalMillis: 3600000, // the iOS SDK defaults this to 900000
-      disableBackgroundUpdating: false,         // the iOS SDK defaults this to true
-      pollUri: 'https://clientsdk.launchdarkly.com',
-      wrapperName: 'react-native-client-sdk',
-      wrapperVersion: this.getVersion()
-    }, config);
-    
-    if (timeout == undefined) {
-      return LaunchdarklyReactNativeClient.configure(configWithOverriddenDefaults, this._addUserOverrides(user));
-    } else {
-      return LaunchdarklyReactNativeClient.configureWithTimeout(configWithOverriddenDefaults, this._addUserOverrides(user), timeout);
-    }
+    return LaunchdarklyReactNativeClient.isInitialized("default")
+      .then(
+        ignored => {
+          throw new Error('LaunchDarkly SDK already initialized');
+        },
+        () => {
+          const configWithOverriddenDefaults = Object.assign({
+            backgroundPollingIntervalMillis: 3600000, // the iOS SDK defaults this to 900000
+            disableBackgroundUpdating: false,         // the iOS SDK defaults this to true
+            pollUri: 'https://clientsdk.launchdarkly.com',
+            wrapperName: 'react-native-client-sdk',
+            wrapperVersion: this.getVersion()
+          }, config);
+
+          if (timeout == undefined) {
+            return LaunchdarklyReactNativeClient.configure(configWithOverriddenDefaults, this._addUserOverrides(user));
+          } else {
+            return LaunchdarklyReactNativeClient.configureWithTimeout(configWithOverriddenDefaults, this._addUserOverrides(user), timeout);
+          }
+        }
+      );
   }
 
   boolVariation(flagKey, defaultValue, environment) {
diff --git a/ios/LaunchdarklyReactNativeClient.swift b/ios/LaunchdarklyReactNativeClient.swift
index e389c33..5344588 100644
--- a/ios/LaunchdarklyReactNativeClient.swift
+++ b/ios/LaunchdarklyReactNativeClient.swift
@@ -11,6 +11,7 @@ class LaunchdarklyReactNativeClient: RCTEventEmitter {
     private let CONNECTION_MODE_PREFIX = "LaunchDarkly-Connection-Mode-"
     private let ERROR_INIT = "E_INITIALIZE"
     private let ERROR_IDENTIFY = "E_IDENTIFY"
+    private let ERROR_UNKNOWN = "E_UNKNOWN"
     
     override func supportedEvents() -> [String]! {
         return [FLAG_PREFIX, ALL_FLAGS_PREFIX, CONNECTION_MODE_PREFIX]
@@ -605,9 +606,11 @@ class LaunchdarklyReactNativeClient: RCTEventEmitter {
 
     @objc func isInitialized(_ environment: String, resolve: RCTPromiseResolveBlock, reject: RCTPromiseRejectBlock) -> Void {
         if LDClient.get() == nil {
-            resolve(false)
+            reject(ERROR_UNKNOWN, "SDK has not been configured", nil)
+        } else if let client = LDClient.get(environment: environment) {
+            resolve(client.isInitialized)
         } else {
-            resolve(LDClient.get(environment: environment)!.isInitialized)
+            reject(ERROR_UNKNOWN, "SDK not configured with requested environment", nil)
         }
     }
 }
diff --git a/ios/LaunchdarklyReactNativeClientBridge.m b/ios/LaunchdarklyReactNativeClientBridge.m
index 76bf0c3..835e4b2 100644
--- a/ios/LaunchdarklyReactNativeClientBridge.m
+++ b/ios/LaunchdarklyReactNativeClientBridge.m
@@ -5,7 +5,7 @@ @interface RCT_EXTERN_MODULE(LaunchdarklyReactNativeClient, RCTEventEmitter)
 
 RCT_EXTERN_METHOD(configure:(NSDictionary *)config user:(NSDictionary *)user resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject)
 
-RCT_EXTERN_METHOD(configureWithTimeout:(NSDictionary *)config userConfig:(NSDictionary *)userConfig timeout:(NSInteger *)timeout resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject)
+RCT_EXTERN_METHOD(configureWithTimeout:(NSDictionary *)config user:(NSDictionary *)user timeout:(NSInteger *)timeout resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject)
 
 RCT_EXTERN_METHOD(boolVariationDefaultValue:(NSString *)flagKey defaultValue:(BOOL *)defaultValue environment:(NSString *)environment resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject)