# Troubleshooting

## Common issues and solutions <a href="#common-issues-and-solutions" id="common-issues-and-solutions"></a>

### 1. Contract calls fail with `EVM error: NotActivated` <a href="#id-1-contract-calls-fail-with-evm-error-notactivated" id="id-1-contract-calls-fail-with-evm-error-notactivated"></a>

The contract has been compiled at a newer EVM version than supported by Alpen. Ensure the EVM version of the compiler is set to `Prague`.

### 2. I get `Could Not Fetch chain ID` error on my wallet <a href="#id-1-contract-calls-fail-with-evm-error-notactivated" id="id-1-contract-calls-fail-with-evm-error-notactivated"></a>

Alpen testnet was updated from Shanghai to Prague specifications on December 4, 2025, doing a network regenesis with a different chain ID. Check that your wallet is using the [current chain ID](/welcome/get-started.md#network-details).

### 3. Alpen CLI returns `Failed to sync signet wallet` error <a href="#id-1-contract-calls-fail-with-evm-error-notactivated" id="id-1-contract-calls-fail-with-evm-error-notactivated"></a>

Check that your Alpen CLI configuration file `~/.config/alpen/config.toml` uses the correct endpoints from [Using the Alpen CLI](/welcome/using-the-alpen-cli.md#user-content-configure-the-cli), then follow the instructions to backup, restore, and scan your CLI wallet balances.

### 4. My full node's strata\_client exits with a `fork_choice_manager` error <a href="#id-1-contract-calls-fail-with-evm-error-notactivated" id="id-1-contract-calls-fail-with-evm-error-notactivated"></a>

Verify that in your configuration file `~/alpen/docker/configs/config.fn.toml` the parameter `sync_endpoint` correctly points to `ws://fnclient675f9eff3a682b8c0ea7423.testnet.alpenlabs.io` .

After you update the file, shut down all containers, delete the contents of `~/alpen/docker/data` folder, and let it resync from zero.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.alpenlabs.io/build-alpen-apps/troubleshooting.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.