diff --git a/WordPress/Classes/Services/PostCategoryService.m b/WordPress/Classes/Services/PostCategoryService.m
index 0b6bef831d30..5451af41593a 100644
--- a/WordPress/Classes/Services/PostCategoryService.m
+++ b/WordPress/Classes/Services/PostCategoryService.m
@@ -31,18 +31,23 @@ - (void)syncCategoriesForBlog:(Blog *)blog
     id<TaxonomyServiceRemote> remote = [self remoteForBlog:blog];
     NSManagedObjectID *blogID = blog.objectID;
     [remote getCategoriesWithSuccess:^(NSArray *categories) {
+                               NSError * __block error = nil;
                                [[ContextManager sharedInstance] performAndSaveUsingBlock:^(NSManagedObjectContext *context) {
                                    Blog *blog = (Blog *)[context existingObjectWithID:blogID error:nil];
                                    if (!blog) {
-                                       if (failure) {
-                                           failure([self serviceErrorNoBlog]);
-                                       }
+                                       error = [self serviceErrorNoBlog];
                                        return;
                                    }
                                    [self mergeCategories:categories forBlog:blog inContext:context];
                                } completion: ^{
-                                   if (success) {
-                                       success();
+                                   if (error) {
+                                       if (failure) {
+                                           failure(error);
+                                       }
+                                   } else {
+                                       if (success) {
+                                           success();
+                                       }
                                    }
                                } onQueue: dispatch_get_main_queue()];
                            } failure:failure];
diff --git a/WordPress/WordPressTest/PostCategoryServiceTests.m b/WordPress/WordPressTest/PostCategoryServiceTests.m
index 297bd8316a5b..7bf9ceca8bbc 100644
--- a/WordPress/WordPressTest/PostCategoryServiceTests.m
+++ b/WordPress/WordPressTest/PostCategoryServiceTests.m
@@ -126,4 +126,30 @@ - (void)testThatCreateCategoryWithNameWorks
                                  failure:^(NSError * _Nonnull error) {}];
 }
 
+- (void)testSyncSuccessShouldBeCalledOnce
+{
+    TaxonomyServiceRemoteREST *remote = self.service.remoteForStubbing;
+
+    XCTestExpectation *completion = [self expectationWithDescription:@"Only the success block is called"];
+    OCMStub([remote getCategoriesWithSuccess:[OCMArg invokeBlock]
+                                     failure:[OCMArg isNotNil]]);
+    [self.service syncCategoriesForBlog:self.blog
+                                success:^{ [completion fulfill]; }
+                                failure:^(NSError * _Nonnull error) {[completion fulfill]; }];
+    [self waitForExpectations:@[completion] timeout:1];
+}
+
+- (void)testSyncFailureShouldBeCalledOnce
+{
+    TaxonomyServiceRemoteREST *remote = self.service.remoteForStubbing;
+
+    XCTestExpectation *completion = [self expectationWithDescription:@"Only the failure block is called"];
+    OCMStub([remote getCategoriesWithSuccess:[OCMArg isNotNil]
+                                     failure:[OCMArg invokeBlock]]);
+    [self.service syncCategoriesForBlog:self.blog
+                                success:^{ [completion fulfill]; }
+                                failure:^(NSError * _Nonnull error) {[completion fulfill]; }];
+    [self waitForExpectations:@[completion] timeout:1];
+}
+
 @end