[SDK 54] AWS Amplify Auth (Cognito v5) – TypeError: Cannot read property 'computeModPow' of null on login

[pvaras8]

Before opening, please confirm:

• I have searched for duplicate or closed issues and discussions.
• I have read the guide for submitting bug reports.
• I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.

JavaScript Framework

React Native

Amplify APIs

Authentication

Amplify Version

v5

Amplify Categories

auth

Backend

Amplify CLI

Environment information

System:
  OS: macOS 15.7 (arm64 Apple M3 Pro)
Binaries:
  Node: 23.5.0
  Yarn: 1.22.22
  npm: 10.9.2
  Watchman: 2024.12.02.00
Packages:
  aws-amplify: 5.3.27
  aws-amplify-react-native: 7.0.8
  amazon-cognito-identity-js: 6.3.14
  expo: 54.0.10
  react-native: 0.81.4
  react: 19.1.0
Global:
  @aws-amplify/cli: 14.0.1
  eas-cli: 16.19.3
  expo-cli: 6.3.10

Describe the bug

After upgrading my project to Expo SDK 54 (React Native 0.81.4), the login flow with Amplify Auth (Cognito v5) stopped working.
Calling Auth.signIn(username, password) now throws:
TypeError: Cannot read property 'computeModPow' of null

Expected behavior

Login with Amplify Auth (Cognito v5) should succeed without errors, just as it did before upgrading to Expo SDK 54.
The call to Auth.signIn(username, password) should return the authenticated user/session object instead of throwing a computeModPow error.

Reproduction steps

Code Snippet

// Put your code below this line.

Log output

// Put your logs below this line

aws-exports.js

No response

Manual configuration

No response

Additional configuration

No response

Mobile Device

No response

Mobile Operating System

No response

Mobile Browser

No response

Mobile Browser Version

No response

Additional information and screenshots

No response

[pranavosu]

Hey @pvaras8, thanks for reporting this! The computeModPow error typically points to an issue with the cryptographic operations used during Cognito's SRP authentication flow.

A few questions to help narrow this down:

Timing & Platform:

• Did authentication work correctly before upgrading to Expo SDK 54?
• Are you seeing this on iOS, Android, or both?

Setup & Dependencies:

• Can you share how you're initializing Amplify and any relevant code around your Auth.signIn() call?
• Do you have react-native-get-random-values imported at the top of your entry file (before any Amplify imports)? This is required for crypto operations.

Environment:

• Have you tried the usual cleanup steps? (delete node_modules, reinstall, clear Metro cache with npx expo start -c)
• Are you seeing any other warnings or errors in the console before this one appears?

The Expo SDK 54 / React Native 0.81 upgrade may have changed some underlying crypto or polyfill requirements. If you can share a bit more about your setup and a code snippet showing your Amplify
configuration + sign-in call, that would really help us figure out what's going on

Thanks,
Pranav