diff --git a/packages/protocol/contracts/layer1/based/LibProposing.sol b/packages/protocol/contracts/layer1/based/LibProposing.sol
index b16d72a9b7b..ee76a93842d 100644
--- a/packages/protocol/contracts/layer1/based/LibProposing.sol
+++ b/packages/protocol/contracts/layer1/based/LibProposing.sol
@@ -36,6 +36,7 @@ library LibProposing {
 
     error L1_BLOB_NOT_AVAILABLE();
     error L1_BLOB_NOT_FOUND();
+    error L1_FORK_HEIGHT_ERROR();
     error L1_INVALID_ANCHOR_BLOCK();
     error L1_INVALID_CUSTOM_PROPOSER();
     error L1_INVALID_PARAMS();
@@ -130,9 +131,11 @@ library LibProposing {
         // It's essential to ensure that the ring buffer for proposed blocks still has space for at
         // least one more block.
         unchecked {
-            if (local.b.numBlocks >= local.b.lastVerifiedBlockId + _config.blockMaxProposals + 1) {
-                revert L1_TOO_MANY_BLOCKS();
-            }
+            require(local.b.numBlocks >= _config.ontakeForkHeight, L1_FORK_HEIGHT_ERROR());
+            require(
+                local.b.numBlocks < local.b.lastVerifiedBlockId + _config.blockMaxProposals + 1,
+                L1_TOO_MANY_BLOCKS()
+            );
         }
 
         address preconfTaskManager = _resolver.resolve(LibStrings.B_PRECONF_TASK_MANAGER, true);
diff --git a/packages/protocol/contracts/layer1/based/TaikoL1.sol b/packages/protocol/contracts/layer1/based/TaikoL1.sol
index bce9eb6daba..871aa363b8d 100644
--- a/packages/protocol/contracts/layer1/based/TaikoL1.sol
+++ b/packages/protocol/contracts/layer1/based/TaikoL1.sol
@@ -25,6 +25,8 @@ contract TaikoL1 is EssentialContract, ITaikoL1, TaikoEvents {
 
     uint256[50] private __gap;
 
+    error L1_FORK_HEIGHT_ERROR();
+
     modifier whenProvingNotPaused() {
         if (state.slotB.provingPaused) revert LibProving.L1_PROVING_PAUSED();
         _;
@@ -179,12 +181,16 @@ contract TaikoL1 is EssentialContract, ITaikoL1, TaikoEvents {
     /// @param _blockId Index of the block.
     /// @return blk_ The block.
     function getBlock(uint64 _blockId) external view returns (TaikoData.Block memory blk_) {
+        require(_blockId < getConfig().ontakeForkHeight, L1_FORK_HEIGHT_ERROR());
+
         (TaikoData.BlockV2 memory blk,) = LibUtils.getBlock(state, getConfig(), _blockId);
         blk_ = LibData.blockV2ToV1(blk);
     }
 
     /// @inheritdoc ITaikoL1
     function getBlockV2(uint64 _blockId) external view returns (TaikoData.BlockV2 memory blk_) {
+        require(_blockId >= getConfig().ontakeForkHeight, L1_FORK_HEIGHT_ERROR());
+
         (blk_,) = LibUtils.getBlock(state, getConfig(), _blockId);
     }
 
diff --git a/packages/protocol/test/layer1/based/TaikoL1.t.sol b/packages/protocol/test/layer1/based/TaikoL1.t.sol
index d950a1c777a..3289979f193 100644
--- a/packages/protocol/test/layer1/based/TaikoL1.t.sol
+++ b/packages/protocol/test/layer1/based/TaikoL1.t.sol
@@ -11,6 +11,7 @@ contract TaikoL1_NoCooldown is TaikoL1 {
         config.blockMaxProposals = 10;
         config.blockRingBufferSize = 12;
         config.livenessBond = 1e18; // 1 Taiko token
+        config.ontakeForkHeight = 0;
     }
 }
 
diff --git a/packages/protocol/test/layer1/based/TaikoL1LibProvingWithTiers.t.sol b/packages/protocol/test/layer1/based/TaikoL1LibProvingWithTiers.t.sol
index 04d8f2da1eb..d27eb8a968c 100644
--- a/packages/protocol/test/layer1/based/TaikoL1LibProvingWithTiers.t.sol
+++ b/packages/protocol/test/layer1/based/TaikoL1LibProvingWithTiers.t.sol
@@ -11,6 +11,7 @@ contract TaikoL1Tiers is TaikoL1 {
         config.blockMaxProposals = 10;
         config.blockRingBufferSize = 12;
         config.livenessBond = 1e18; // 1 Taiko token
+        config.ontakeForkHeight = 0;
     }
 }
 
diff --git a/packages/protocol/test/layer1/based/TaikoL1TestGroupBase.sol b/packages/protocol/test/layer1/based/TaikoL1TestGroupBase.sol
index 5d45d0ef695..6accc380dc8 100644
--- a/packages/protocol/test/layer1/based/TaikoL1TestGroupBase.sol
+++ b/packages/protocol/test/layer1/based/TaikoL1TestGroupBase.sol
@@ -10,6 +10,7 @@ contract TaikoL1New is TaikoL1 {
         config.blockMaxProposals = 20;
         config.blockRingBufferSize = 25;
         config.stateRootSyncInternal = 2;
+        config.ontakeForkHeight = 0;
     }
 }