diff --git a/.changeset/new-penguins-end.md b/.changeset/new-penguins-end.md
new file mode 100644
index 0000000000..96439d7211
--- /dev/null
+++ b/.changeset/new-penguins-end.md
@@ -0,0 +1,5 @@
+---
+"@farcaster/hubble": minor
+---
+
+feat: Make l2 rpc url required to start hubble ahead of mainnet migration
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 52f021b5e9..f1f068de16 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -36,7 +36,7 @@ jobs:
 
       - name: Run Hubble
         shell: bash
-        run: docker run --name hub --detach -p2282:2282 -p2283:2283 farcasterxyz/hubble:test sh -c 'node build/cli.js identity create && node build/cli.js start --rpc-port 2283 --ip 0.0.0.0 --gossip-port 2282 --eth-rpc-url "https://eth-goerli.g.alchemy.com/v2/IvjMoCKt1hT66f9OJoL_dMXypnvQYUdd" --eth-mainnet-rpc-url "https://eth-mainnet.g.alchemy.com/v2/8cz__IXnQ5FK_GNYDlfooLzYhBAW7ta0" --network 3 --allowed-peers none'
+        run: docker run --name hub --detach -p2282:2282 -p2283:2283 farcasterxyz/hubble:test sh -c 'node build/cli.js identity create && node build/cli.js start --rpc-port 2283 --ip 0.0.0.0 --gossip-port 2282 --eth-rpc-url "https://eth-goerli.g.alchemy.com/v2/IvjMoCKt1hT66f9OJoL_dMXypnvQYUdd" --eth-mainnet-rpc-url "https://eth-mainnet.g.alchemy.com/v2/8cz__IXnQ5FK_GNYDlfooLzYhBAW7ta0" --l2-rpc-url "https://opt-mainnet.g.alchemy.com/v2/3xWX-cWV-an3IPXmVCRXX51PpQzc-8iJ" --network 3 --allowed-peers none'
 
       - name: Download grpcurl
         shell: bash
diff --git a/apps/hubble/src/cli.ts b/apps/hubble/src/cli.ts
index b310747d70..a337b9bea4 100644
--- a/apps/hubble/src/cli.ts
+++ b/apps/hubble/src/cli.ts
@@ -513,7 +513,13 @@ app
 
     await startupCheck.rpcCheck(options.ethRpcUrl, goerli, "L1");
     await startupCheck.rpcCheck(options.ethMainnetRpcUrl, mainnet, "L1");
-    await startupCheck.rpcCheck(options.l2RpcUrl, optimism, "L2");
+    await startupCheck.rpcCheck(options.l2RpcUrl, optimism, "L2", options.l2ChainId);
+
+    if (startupCheck.anyFailedChecks()) {
+      logger.fatal({ reason: "Startup checks failed" }, "shutting down hub");
+      logger.flush();
+      process.exit(1);
+    }
 
     const hubResult = Result.fromThrowable(
       () => new Hub(options),
diff --git a/apps/hubble/src/hubble.ts b/apps/hubble/src/hubble.ts
index 1bdd377425..460d384e37 100644
--- a/apps/hubble/src/hubble.ts
+++ b/apps/hubble/src/hubble.ts
@@ -332,7 +332,8 @@ export class Hub implements HubInterface {
         options.l2RentExpiryOverride,
       );
     } else {
-      log.warn("No L2 RPC URL provided, not syncing with L2 contract events");
+      log.warn("No L2 RPC URL provided, unable to sync L2 contract events");
+      throw new HubError("bad_request.invalid_param", "Invalid l2 rpc url");
     }
 
     if (options.fnameServerUrl && options.fnameServerUrl !== "") {
diff --git a/apps/hubble/src/utils/startupCheck.ts b/apps/hubble/src/utils/startupCheck.ts
index d2947b45f3..cde9da9387 100644
--- a/apps/hubble/src/utils/startupCheck.ts
+++ b/apps/hubble/src/utils/startupCheck.ts
@@ -60,7 +60,13 @@ class StartupCheck {
     }
   }
 
-  async rpcCheck(rpcUrl: string | undefined, chain: Chain, prefix = "", status = StartupCheckStatus.ERROR) {
+  async rpcCheck(
+    rpcUrl: string | undefined,
+    chain: Chain,
+    prefix = "",
+    chainId?: number,
+    status = StartupCheckStatus.ERROR,
+  ) {
     const type = chain.name;
     if (!rpcUrl) {
       this.printStartupCheckStatus(
@@ -82,7 +88,7 @@ class StartupCheck {
     // Check that the publicClient is reachable and returns the goerli chainId
     const chainIdResult = await ResultAsync.fromPromise(publicClient.getChainId(), (err) => err);
 
-    if (chainIdResult.isErr() || chainIdResult.value !== chain.id) {
+    if (chainIdResult.isErr() || chainIdResult.value !== (chainId ?? chain.id)) {
       console.log(chainIdResult);
       this.printStartupCheckStatus(
         status,