diff --git a/quic/codec/PacketNumber.cpp b/quic/codec/PacketNumber.cpp
index 8685196da..bfc0996f2 100644
--- a/quic/codec/PacketNumber.cpp
+++ b/quic/codec/PacketNumber.cpp
@@ -11,7 +11,6 @@
 #include <quic/QuicConstants.h>
 #include <quic/QuicException.h>
 #include <quic/codec/PacketNumber.h>
-#include <string>
 
 namespace quic {
 
@@ -29,15 +28,8 @@ PacketNumEncodingResult encodePacketNumber(
   size_t lengthInBits = folly::findLastSet(twiceDistance);
   // Round up to bytes
   size_t lengthInBytes = lengthInBits == 0 ? 1 : (lengthInBits + 7) >> 3;
-  if (lengthInBytes > 4) {
-    throw QuicInternalException(
-        folly::to<std::string>(
-            "Impossible to encode PacketNum=",
-            packetNum,
-            ", largestAcked=",
-            largestAckedPacketNum),
-        LocalErrorCode::PACKET_NUMBER_ENCODING);
-  }
+  CHECK(lengthInBytes <= 4) << "Impossible to encode PacketNum=" << packetNum
+                            << ", largestAcked=" << largestAckedPacketNum;
   // We need a mask that's all 1 for lengthInBytes bytes. Left shift a 1 by that
   // many bits and then -1 will give us that. Or if lengthInBytes is 8, then ~0
   // will just do it.
diff --git a/quic/codec/QuicInteger.h b/quic/codec/QuicInteger.h
index 78ef8a418..eae16d7d9 100644
--- a/quic/codec/QuicInteger.h
+++ b/quic/codec/QuicInteger.h
@@ -136,22 +136,14 @@ class QuicInteger {
   template <typename BufOp>
   size_t encode(BufOp appender) const {
     auto size = encodeQuicInteger(value_, std::move(appender));
-    if (size.hasError()) {
-      LOG(ERROR) << "Value too large value=" << value_;
-      throw QuicTransportException(
-          folly::to<std::string>("Value too large ", value_), size.error());
-    }
+    CHECK(!size.hasError()) << "Value too large value=" << value_;
     return size.value();
   }
 
   template <typename BufOp>
   size_t encode(BufOp appender, int outputSize) const {
     auto size = encodeQuicInteger(value_, std::move(appender), outputSize);
-    if (size.hasError()) {
-      LOG(ERROR) << "Value too large value=" << value_;
-      throw QuicTransportException(
-          folly::to<std::string>("Value too large ", value_), size.error());
-    }
+    CHECK(!size.hasError()) << "Value too large value=" << value_;
     return size.value();
   }
 
diff --git a/quic/codec/QuicWriteCodec.cpp b/quic/codec/QuicWriteCodec.cpp
index c52fa7dee..c9fa8ba95 100644
--- a/quic/codec/QuicWriteCodec.cpp
+++ b/quic/codec/QuicWriteCodec.cpp
@@ -106,8 +106,7 @@ folly::Expected<Optional<uint64_t>, QuicError> writeStreamFrameHeader(
     } else {
       // This should never really happen as dataLen is bounded by the remaining
       // space in the packet which should be << kEightByteLimit.
-      throw QuicInternalException(
-          "Stream frame length too large.", LocalErrorCode::INTERNAL_ERROR);
+      LOG(FATAL) << "Stream frame length too large.";
     }
   }
   if (dataLenLen > 0) {
@@ -198,11 +197,8 @@ Optional<WriteCryptoFrame> writeCryptoFrame(
   size_t writableData = std::min(dataLength, spaceRemaining);
   QuicInteger lengthVarInt(writableData);
 
-  if (lengthVarInt.getSize() > lengthBytes) {
-    throw QuicInternalException(
-        std::string("Length bytes representation"),
-        LocalErrorCode::CODEC_ERROR);
-  }
+  CHECK(lengthVarInt.getSize() <= lengthBytes)
+      << "Length bytes representation exceeds allocated space";
   builder.write(intFrameType);
   builder.write(offsetInteger);
   builder.write(lengthVarInt);
@@ -1070,11 +1066,7 @@ size_t writeFrame(QuicWriteFrame&& frame, PacketBuilderInterface& builder) {
       return size_t(0);
     }
     default: {
-      auto errorStr = folly::to<std::string>(
-          "Unknown / unsupported frame type received at ", __func__);
-      VLOG(2) << errorStr;
-      throw QuicTransportException(
-          errorStr, TransportErrorCode::FRAME_ENCODING_ERROR);
+      LOG(FATAL) << "Unknown / unsupported frame type received";
     }
   }
 }
diff --git a/quic/codec/Types.cpp b/quic/codec/Types.cpp
index 2feb2d387..c7cd60758 100644
--- a/quic/codec/Types.cpp
+++ b/quic/codec/Types.cpp
@@ -255,21 +255,19 @@ ShortHeader::ShortHeader(
     ConnectionId connId,
     PacketNum packetNum)
     : protectionType_(protectionType), connectionId_(std::move(connId)) {
-  if (protectionType_ != ProtectionType::KeyPhaseZero &&
-      protectionType_ != ProtectionType::KeyPhaseOne) {
-    throw QuicInternalException(
-        "bad short header protection type", LocalErrorCode::CODEC_ERROR);
-  }
+  CHECK(
+      protectionType_ == ProtectionType::KeyPhaseZero ||
+      protectionType_ == ProtectionType::KeyPhaseOne)
+      << "bad short header protection type";
   setPacketNumber(packetNum);
 }
 
 ShortHeader::ShortHeader(ProtectionType protectionType, ConnectionId connId)
     : protectionType_(protectionType), connectionId_(std::move(connId)) {
-  if (protectionType_ != ProtectionType::KeyPhaseZero &&
-      protectionType_ != ProtectionType::KeyPhaseOne) {
-    throw QuicInternalException(
-        "bad short header protection type", LocalErrorCode::CODEC_ERROR);
-  }
+  CHECK(
+      protectionType_ == ProtectionType::KeyPhaseZero ||
+      protectionType_ == ProtectionType::KeyPhaseOne)
+      << "bad short header protection type";
 }
 
 ProtectionType ShortHeader::getProtectionType() const {