Comment by CodesInChaos
17 hours ago
This is usually caused by an insufficently seeded PRNG.
Are you generating the UUID in the backend, or the frontend? Frontend is fundamentally unreliable for many reasons, including deliberate collisions. So if that case you'll need to handle collisions somehow. Though you can still engineer around common sources of collisions, the specifics depend on the environment.
On the other hand making a backend reliable is feasible. What kind of environment is your code running in? Historically VMs sometimes suffered from this problem, though this should be solved nowadays. Heavily sandboxed processes might still run into this, if the RNG library uses an unsafe fallback. Forking processes or VMs can cause state duplication and thus collisions.
I remember hearing about Segment (analytics company) had their entire product based around UUIDs generated in web browsers. There were collisions all over the place, the product was seemingly incapable of producing useful data at a fundamental level because of it. Hopefully they've fixed that now.