How to fix IncompleteSignatureException: The request signature does not conform to AWS standards in DynamoDB

First, confirm that your AWS Access Key ID and Secret Access Key are correct and still active:

1. Go to the AWS IAM Console (https://console.aws.amazon.com/iam/)
2. Navigate to "Users" and select your user
3. In the "Security credentials" tab, check your Access Keys:
- If you have multiple access keys, delete any you're not using
- Create a new Access Key pair if your current one is invalid or missing
4. Update your AWS credentials in your environment variables or config file:

For environment variables:

export AWS_ACCESS_KEY_ID=your_access_key
export AWS_SECRET_ACCESS_KEY=your_secret_key
export AWS_REGION=us-east-1  # Use your correct region

For AWS credentials file (~/.aws/credentials on Linux/Mac or C:\Users\USERNAME\.aws\credentials on Windows):

[default]
aws_access_key_id = your_access_key
aws_secret_access_key = your_secret_key

For AWS config file (~/.aws/config):

[default]
region = us-east-1

If using temporary credentials from AWS STS, make sure they haven't expired by checking the expiration date in your security token.

AWS rejects requests if your system time is more than 15 minutes off from the current time. This is because the signature includes a timestamp that AWS validates:

On Linux/Mac:

# Check your current system time
date

# Install NTP (Network Time Protocol) if not already installed
sudo apt-get install ntp  # Ubuntu/Debian
sudo yum install ntp      # CentOS/RHEL
brew install ntp          # macOS

# Start the NTP service
sudo systemctl start ntp
sudo systemctl enable ntp

# Or use timedatectl (systemd-based systems)
timedatectl set-ntp true
timedatectl status

On Windows:

# Check system time
Get-Date

# Sync time with Windows Time service
w32tm /resync

After syncing, retry your DynamoDB operation.

The most reliable way to fix signature issues is to use an official AWS SDK, which handles all signing details automatically. If you're already using an SDK, upgrade to the latest version:

For Node.js/JavaScript:

npm install @aws-sdk/client-dynamodb@latest

For Python:

pip install --upgrade boto3

For Java:

# Update your Maven pom.xml or Gradle build file with the latest SDK version

For other languages, download the latest SDK from https://aws.amazon.com/tools/

Example using AWS SDK for JavaScript:

const { DynamoDBClient, GetItemCommand } = require("@aws-sdk/client-dynamodb");

const client = new DynamoDBClient({ region: "us-east-1" });

const command = new GetItemCommand({
  TableName: "YourTableName",
  Key: { id: { S: "test-id" } },
});

client.send(command)
  .then(data => console.log("Success:", data))
  .catch(error => console.error("Error:", error));

If you're manually constructing signatures (rare), switch to using your SDK instead.

The region must match where your DynamoDB table exists. If you specify the wrong region, the signature won't match AWS's expectations:

For Node.js:

const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");

const client = new DynamoDBClient({
  region: "us-east-1", // Change to your table's region
  credentials: {
    accessKeyId: process.env.AWS_ACCESS_KEY_ID,
    secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
  },
});

For Python (Boto3):

import boto3

dynamodb = boto3.client('dynamodb', region_name='us-east-1')

Check the AWS Management Console to find your table's region, then update your client configuration.

If you're behind a corporate proxy, firewall, or load balancer, it may be modifying the Authorization header. To debug this:

1. Add logging to capture the actual headers being sent:

For Node.js:

const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");

const client = new DynamoDBClient({
  region: "us-east-1",
  logger: console, // Enable debug logging
});

For Python:

import boto3
import logging

logging.basicConfig(level=logging.DEBUG)
boto3.set_stream_logger('', logging.DEBUG)

dynamodb = boto3.client('dynamodb', region_name='us-east-1')

2. If you see the Authorization header being modified or stripped, you'll need to:
- Configure your proxy to allow AWS authentication headers to pass through
- Contact your network administrator
- Use an AWS VPC endpoint for DynamoDB if inside a private network (https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/vpc-endpoints-dynamodb.html)

Use the AWS CLI to isolate whether the issue is with your code or your credentials:

# Configure your credentials
aws configure

# Test a simple DynamoDB operation
aws dynamodb list-tables --region us-east-1

# If that works, test getting an item from your table
aws dynamodb get-item \
  --table-name YourTableName \
  --key '{"id":{"S":"test-id"}}' \
  --region us-east-1

If the CLI works but your code doesn't, the issue is likely in how you're configuring your client or credentials in your application code.