I am in the process of updating an existing project from react-native 0.60.4 to 0.61.2. The app is successfully packaged and installs on my local iOS Simulator. The Metro Bundler successfully serves the app to the device. My observations are as follows:

• Upon running, a red screen error headlined TypeError: hmrClient.send is not a function. is displayed on every launch, regardless of whether Fast Refresh is enabled or disabled.
• This red screen message can be dismissed, and underneath I have a functional, navigable application.
• No Fast Refresh functionality works when enabled, most likely tied directly to this.

React Native version:

yarn run v1.19.1
$ /Users/alex/Development/<project>/node_modules/.bin/react-native info
info Fetching system and libraries information...
System:
    OS: macOS 10.15
    CPU: (4) x64 Intel(R) Core(TM) i7-7660U CPU @ 2.50GHz
    Memory: 141.59 MB / 16.00 GB
    Shell: 3.0.2 - /usr/local/bin/fish
  Binaries:
    Node: 10.16.3 - /var/folders/t_/q6_rnx915r38lst_z95l6swh0000gn/T/yarn--1571762447670-0.2398560026433516/node
    Yarn: 1.19.1 - /var/folders/t_/q6_rnx915r38lst_z95l6swh0000gn/T/yarn--1571762447670-0.2398560026433516/yarn
    npm: 6.11.3 - ~/.config/nvm/10.16.3/bin/npm
    Watchman: 4.9.0 - /usr/local/bin/watchman
  SDKs:
    iOS SDK:
      Platforms: iOS 13.0, DriverKit 19.0, macOS 10.15, tvOS 13.0, watchOS 6.0
    Android SDK:
      API Levels: 28, 29
      Build Tools: 28.0.3, 29.0.2
      System Images: android-29 | Google APIs Intel x86 Atom
  IDEs:
    Android Studio: 3.5 AI-191.8026.42.35.5900203
    Xcode: 11.0/11A420a - /usr/bin/xcodebuild
  npmPackages:
    react: 16.9.0 => 16.9.0 
    react-native: 0.61.2 => 0.61.2
Done in 7.47s.

Error output

TypeError: hmrClient.send is not a function. (In 'hmrClient.send(JSON.stringify({
        type: 'log-opt-in'
      }))', 'hmrClient.send' is undefined)

enable
    HMRClient.js:70:19
setup
    HMRClient.js:241:6
callFunctionReturnFlushedQueue
    [native code]:0

Other notes

Interestingly, this isn't caught by this preceding invariant statement in the enable or disable members of HMRClient. I suspect it's related to some misalignment within HMRClient.js or any corresponding native code.

https://github.com/facebook/react-native/blob/10f55e752d1b3e1fd9b993a72c692750118f0608/Libraries/Utilities/HMRClient.js#L67-L72