In my iOS app undefined symbols for architecture x86_64 - ios

Question

Trying to get my app ready for arm64 and updating all my pods. I updated all the pods but getting this error so app will not compile.
Undefined symbols for architecture x86_64:
"_OBJC_CLASS_$_AFHTTPClient", referenced from:
objc-class-ref in MYAPP.o
"_OBJC_CLASS_$_AFJSONRequestOperation", referenced from:
objc-class-ref in MYAPP.o
"_OBJC_CLASS_$_AFNetworkActivityIndicatorManager", referenced from:
objc-class-ref in MYAPP.o
"_OBJC_CLASS_$_RKAttributeMapping", referenced from:
objc-class-ref in MYAPP.o
"_OBJC_CLASS_$_RKEntityMapping", referenced from:
objc-class-ref in MYAPP.o
"_OBJC_CLASS_$_RKErrorMessage", referenced from:
objc-class-ref in MYAPP.o
"_OBJC_CLASS_$_RKManagedObjectStore", referenced from:
objc-class-ref in MYAPP.o
objc-class-ref in NSManagedObject+ActiveRecord.o
"_OBJC_CLASS_$_RKObjectManager", referenced from:
objc-class-ref in MYAPP.o
_OBJC_CLASS_$_STObjectManager in STObjectManager.o
objc-class-ref in NSManagedObject+EasyFetching.o
"_OBJC_CLASS_$_RKObjectMapping", referenced from:
objc-class-ref in MYAPP.o
"_OBJC_CLASS_$_RKRelationshipMapping", referenced from:
objc-class-ref in MYAPP.o
"_OBJC_CLASS_$_RKRequestDescriptor", referenced from:
objc-class-ref in MYAPP.o
"_OBJC_CLASS_$_RKResponseDescriptor", referenced from:
objc-class-ref in MYAPP.o
"_OBJC_CLASS_$_RKRoute", referenced from:
objc-class-ref in MYAPP.o

Answer 1

There's a couple of things that might fix this:
Check Your-Workspace/Build Settings and Pods/Build Settings for the following items: Architectures, Build Active Architecture Only, Valid Architectures. All three should match between both workspaces.
Try cleaning (CMD-Shift-K) and also cleaning the build folder (CMD-Option-Shift-K).

Answer 2

I fixed this by going back from 1.0.1 version to 0.39.0.beta.3 version of cocoapods.