I’m trying to create a Redis OSS cache using Amazon ElastiCache in AWS, but I’m getting “Customer account VPC should have a minimum of 3 default subnets.” I have set up my VPC with multiple subnets and route tables. The details of my setup are:

VPC and Subnets

• VPC ID: vpc-xxxxxxxxxxxxxxxxx
• Subnets:
  • myapp-subnet-public1-us-west-2a (10.0.0.0/20)
  • myapp-subnet-public2-us-west-2b (10.0.16.0/20)
  • myapp-subnet-public3-us-west-2c (10.0.192.0/20) (Auto-assign public IPv4 address enabled)
  • myapp-subnet-private1-us-west-2a (10.0.128.0/20)
  • myapp-subnet-private2-us-west-2b (10.0.144.0/20)
  • myapp-subnet-private3-us-west-2c (10.0.208.0/20)

Route Tables

• myapp-rtb-public3-us-west-2c (Main Route Table)

  • Routes:
    • Destination 0.0.0.0/0 -> Target igw-xxxxxxxxxxxxxxxxx
    • Destination 10.0.0.0/16 -> Target local
  • Subnets without explicit associations:
    • myapp-subnet-public3-us-west-2c
    • myapp-subnet-private3-us-west-2c

• myapp-rtb-public

  • Routes:
    • Destination 0.0.0.0/0 -> Target igw-xxxxxxxxxxxxxxxxx
    • Destination 10.0.0.0/16 -> Target local
  • Explicit Subnet Associations:
    • myapp-subnet-public1-us-west-2a
    • myapp-subnet-public2-us-west-2b

Steps Taken

1. Verified Subnet Configuration:

   • Ensured that the subnets have the correct CIDR blocks and are in the correct Availability Zones.
   • Enabled auto-assign public IPv4 address for all public subnets.
   • Confirmed that the subnets are available and not overlapping in CIDR range.

2. Configured Route Tables:

   • Created route tables and added routes for internet access and local VPC communication.
   • Ensured that the main route table (myapp-rtb-public3-us-west-2c) has routes for 0.0.0.0/0 pointing to the internet gateway and 10.0.0.0/16 pointing to local.
   • Associated public subnets myapp-subnet-public1-us-west-2a and myapp-subnet-public2-us-west-2b explicitly with the myapp-rtb-public route table.

3. Checked Subnet Associations:

   • Verified that the subnets are correctly associated with the appropriate route tables.
   • Made sure that myapp-subnet-public3-us-west-2c is in the main route table (myapp-rtb-public3-us-west-2c).
   • Double-checked that all public subnets are set to auto-assign public IPv4 addresses.

4. Renaming and Consistency:

   • Renamed subnets and route tables to a consistent naming convention to avoid any conflicts.
   • Updated references and associations after renaming to ensure consistency.

5. Validation:

   • Verified the entire setup through the AWS Management Console to ensure no discrepancies.
   • Reviewed all settings and configurations to confirm they align with AWS best practices.

Problem

Despite having the subnets and route tables correctly configured, I am still unable to create the Redis OSS cache and receive the error about needing a minimum of 3 default subnets. What am I missing in my setup? How can I resolve this issue and successfully create the Redis OSS cache?

Additional Information

• All subnets are available and correctly associated with their respective route tables.
• There are no security group or networking constraints that should interfere with the subnet availability.
• The VPC is properly configured and the internet gateway is attached and routed correctly.

Any help or troubleshooting tips would be greatly appreciated!