Pool overlaps with other one on this address space

TL;DR: Pick a subnet that does not collide. Run docker network inspect on existing networks (and ip route for host routes) to see what is taken, then create yours with a free --subnet. The daemon refuses overlapping bridge subnets because routing between them would be ambiguous.

The error

Pool overlaps with other one on this address space

Fix it

1. List subnets already in use by docker: docker network inspect $(docker network ls -q) --format '{{.Name}} {{.IPAM.Config}}' Expected: the subnet list, one of which overlaps yours.

2. Check host routes too (VPNs, VM interfaces): ip route | grep -E "^10\.|^172\.|^192\.168" Expected: host-side ranges to avoid.

3. Create with a free subnet: docker network create --subnet CONTAINER_IP/24 mynet Expected: network created.

When this applies

• docker network create --subnet with a hardcoded range from docs or a compose file
• Moving compose projects between hosts with different network layouts

When this does NOT apply

• "could not find an available pool" (exhaustion, not a specific collision)
• Overlaps reported by a VPN client (fix on the VPN side or renumber docker)

Versions

All Docker Engine versions.

Why it happens

Each bridge network gets its own subnet and the daemon programs iptables/NAT per network. Two networks sharing addresses would make container IPs ambiguous, so the daemon validates against all existing networks and host routes before creating.

Edge cases

• Docker Desktop's internal VM has its own routes; a subnet free on your Mac may collide inside the VM.
• --subnet must include a valid gateway; the daemon picks .1 by default, so avoid assigning that to a container statically.
• Compose files hardcoding ipam.config.subnet from another environment are the most common source; parameterize per environment.