Crash in MediaServiceRemoteREST createMedia

[astralbodies]

App version: 6.7/6.7.0.4 App Store
Device: iPhone 6
Crash report: http://crashes.to/s/f550331e9bb
User report: https://ios.forums.wordpress.org/topic/wordpress-for-ios-crashes-when-uploading-a-photo

Steps to reproduce:

I'm using WordPress 6.6 for iOS on an iPhone 6 running iOS 10.1.1 with the self-hosted zacheverson.com. I've used the app in the distant past and it worked fine.

Yesterday, however, I returned to it and tried to upload a photo into a blog post. After selecting the photo, a grayed-out version of it would appear in the post with "Uploading..." at the top. A blue progress bar appears, but just as it's about to be completed, the app crashes.

The crash report sent in by this user does indicate it is happening with 6.7.

Fatal Exception: NSInvalidArgumentException
-[__NSCFNumber count]: unrecognized selector sent to instance 0xb000000000001933
0  CoreFoundation                 0x185fe11b8 __exceptionPreprocess
1  libobjc.A.dylib                0x184a1855c objc_exception_throw
2  CoreFoundation                 0x185fe8268 __methodDescriptionForSelector
3  CoreFoundation                 0x185fe5270 ___forwarding___
4  CoreFoundation                 0x185ede80c _CF_forwarding_prep_0
5  WordPress                      0x100158060 __63-[MediaServiceRemoteREST createMedia:progress:success:failure:]_block_invoke (MediaServiceRemoteREST.m:144)
6  WordPress                      0x1004189c8 thunk (WordPressOrgXMLRPCApi.swift)
7  WordPress                      0x1004ceedc WordPressComRestApi.(multipartPOST(String, parameters : [String : AnyObject]?, fileParts : [FilePart], success : (responseObject : AnyObject, httpResponse : NSHTTPURLResponse?) -> (), failure : (error : NSError, httpResponse : NSHTTPURLResponse?) -> ()) -> NSProgress?).(closure #3) (WordPressComRestApi.swift)
8  WordPress                      0x1004d39dc partial apply for WordPressComRestApi.(multipartPOST(String, parameters : [String : AnyObject]?, fileParts : [FilePart], success : (responseObject : AnyObject, httpResponse : NSHTTPURLResponse?) -> (), failure : (error : NSError, httpResponse : NSHTTPURLResponse?) -> ()) -> NSProgress?).(closure #3) (WordPressComRestApi.swift)
9  AFNetworking                   0x100a7d4f4 __72-[AFURLSessionManagerTaskDelegate URLSession:task:didCompleteWithError:]_block_invoke_2.150 (AFURLSessionManager.m:308)
10 libdispatch.dylib              0x184e6a1fc _dispatch_call_block_and_release
11 libdispatch.dylib              0x184e6a1bc _dispatch_client_callout
12 libdispatch.dylib              0x184e6eb2c _dispatch_main_queue_callback_4CF
13 CoreFoundation                 0x185f8e810 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__
14 CoreFoundation                 0x185f8c3fc __CFRunLoopRun
15 CoreFoundation                 0x185eba2b8 CFRunLoopRunSpecific
16 GraphicsServices               0x18796e198 GSEventRunModal
17 UIKit                          0x18bf017fc -[UIApplication _run]
18 UIKit                          0x18befc534 UIApplicationMain
19 WordPress                      0x100059c70 main (main.m:5)
20 libdispatch.dylib              0x184e9d5b8 (Missing)

[astralbodies]

In this specific case I think this is caused by a Jetpack misconfiguration causing uploads to fail.

29 | 05:44:04:227 | Failed syncing post formats for blog [REDACTED]: Error Domain=WordPress.WordPressComRestApiError Code=7 "The Jetpack site is inaccessible or returned an error: server error. requested method jetpack.jsonAPI does not exist. [-32601]" UserInfo={WordPressComRestApiErrorCodeKey=jetpack_error, WordPressComRestApiErrorMessageKey=The Jetpack site is inaccessible or returned an error: server error. requested method jetpack.jsonAPI does not exist. [-32601], NSLocalizedDescription=The Jetpack site is inaccessible or returned an error: server error. requested method jetpack.jsonAPI does not exist. [-32601]}