# Match Your SPT & Fika Versions (Server ↔ Client) (/docs/escape-from-tarkov/match-versions)



The single most common connection blocker on SPT-Fika is a **version mismatch** between the server and a player's client. Three things must line up.

The Three Things That Must Match [#the-three-things-that-must-match]

1. **SPT version** — the Single Player Tarkov framework build.
2. **Fika version** — the co-op mod build.
3. **Required client mods** — any mods the server marks as required (see [Server vs Client Mods](/docs/escape-from-tarkov/server-vs-client-mods)).

If any of these differ between the server and a player, that player can't join.

On the Server (Startup Tab) [#on-the-server-startup-tab]

Your server's versions are set on the panel **Startup** tab:

| Variable                 | Example / default       | What it does                                                                                               |
| ------------------------ | ----------------------- | ---------------------------------------------------------------------------------------------------------- |
| `SPT_VERSION`            | `4.0.13-40087…`         | The SPT build the server runs.                                                                             |
| `FIKA_VERSION`           | *(blank = latest)*      | The Fika build to install.                                                                                 |
| `FIKA_MODE`              | `auto-update`           | How Fika updates. `auto-update` keeps Fika current on boot.                                                |
| `FIKA_HEADLESS_PROFILES` | `0`                     | Number of headless profiles to generate — see [Headless Client](/docs/escape-from-tarkov/headless-client). |
| `FIKA_NATPUNCH_PORT`     | *(blank = server port)* | Port for Fika NAT punching — see [Play with Friends](/docs/escape-from-tarkov/play-with-friends).          |

On Each Player's PC [#on-each-players-pc]

Every player installs, matching the server:

1. **SPT** via the official SPT installer, at the same **SPT version** as the server.
2. **Fika** at the same **Fika version** as the server.
3. Any **required mods** the server enforces.

How to Read the Running Versions [#how-to-read-the-running-versions]

The server **Console** prints the SPT and Fika versions at startup. Compare those to what each player has installed. If they differ, update whichever side is behind.

SPT 4.0 vs 3.x [#spt-40-vs-3x]

SPT 4.0 is a ground-up rewrite — **3.x clients and 3.x mods are not compatible with 4.0**. If a mod silently fails to load and the console shows `No Assemblies found in path`, it's a 3.x mod on a 4.0 server. See [Troubleshooting](/docs/escape-from-tarkov/troubleshooting).

Related [#related]

* [Connect to Your Server](/docs/escape-from-tarkov/connect-to-your-server)
* [Install Mods](/docs/escape-from-tarkov/install-mods)
* [Troubleshooting](/docs/escape-from-tarkov/troubleshooting)