Fix Terraform Error - Error Creating Route - RouteAlreadyExists

Quick Answer

A route with that destination CIDR already exists in the route table. Either import the existing route, remove the duplicate definition, or switch from inline routes to separate aws_route resources (or vice versa). Never mix inline and separate routes for the same route table.

The Error

Error creating Route: RouteAlreadyExists: The route identified by 0.0.0.0/0 already exists

Or with specific CIDRs:

Error creating Route: RouteAlreadyExists: The route identified by 10.0.0.0/16 already exists

What Causes This

1. Route Created Outside Terraform

Someone added the route manually in the AWS Console, or another tool created it.

2. Mixing Inline and Separate Route Resources

# ❌ WRONG — this creates the same route twice
resource "aws_route_table" "public" {
  vpc_id = aws_vpc.main.id
  route {
    cidr_block = "0.0.0.0/0"          # Inline route
    gateway_id = aws_internet_gateway.main.id
  }
}
 
resource "aws_route" "internet" {
  route_table_id         = aws_route_table.public.id
  destination_cidr_block = "0.0.0.0/0"  # Separate route — CONFLICT!
  gateway_id             = aws_internet_gateway.main.id
}

3. Duplicate Definitions Across Files

The same route defined in two different .tf files.

4. VPC Default Route Conflict

AWS creates a local route (e.g., 10.0.0.0/16 → local) automatically — you can't override it.

How to Fix It

Solution 1: Import the Existing Route

# Format: route_table_id_destination_cidr
terraform import aws_route.internet rtb-0123456789abcdef0_0.0.0.0/0

Solution 2: Use Only Separate Route Resources (Recommended)

resource "aws_route_table" "public" {
  vpc_id = aws_vpc.main.id
  # NO inline routes
}
 
resource "aws_route" "internet" {
  route_table_id         = aws_route_table.public.id
  destination_cidr_block = "0.0.0.0/0"
  gateway_id             = aws_internet_gateway.main.id
}
 
resource "aws_route" "nat" {
  route_table_id         = aws_route_table.private.id
  destination_cidr_block = "0.0.0.0/0"
  nat_gateway_id         = aws_nat_gateway.main.id
}

Solution 3: Use Only Inline Routes

resource "aws_route_table" "public" {
  vpc_id = aws_vpc.main.id
 
  route {
    cidr_block = "0.0.0.0/0"
    gateway_id = aws_internet_gateway.main.id
  }
 
  route {
    cidr_block                = "10.1.0.0/16"
    vpc_peering_connection_id = aws_vpc_peering_connection.peer.id
  }
}

Solution 4: Find and Remove Duplicates

# Search for duplicate route definitions
grep -rn 'destination_cidr_block.*0.0.0.0/0' *.tf modules/**/*.tf

Inline vs Separate Routes

Rule: Pick one approach per route table and stick with it.

Troubleshooting Checklist

1. ✅ Is the route defined both inline and as a separate resource?
2. ✅ Was the route created manually in AWS Console?
3. ✅ Is the same CIDR defined in multiple .tf files?
4. ✅ Are you trying to override the VPC's local route?

Prevention Tips

• Choose inline OR separate routes — never mix per route table
• Import manually-created routes before adding them to Terraform
• Use terraform plan to catch conflicts before applying
• Search for duplicates when adding new routes

Related Articles

• Terraform Troubleshooting - Common Errors and Solutions
• Terraform on AWS Guide
• Terraform Glossary

Conclusion

RouteAlreadyExists means the route exists — either outside Terraform or as a duplicate definition. Import it, remove the duplicate, and never mix inline and separate route resources on the same route table.