diff --git a/api/transport/stun.cc b/api/transport/stun.cc
index 97da5082e7..c359fd359d 100644
--- a/api/transport/stun.cc
+++ b/api/transport/stun.cc
@@ -587,7 +587,7 @@ bool StunMessage::AddFingerprint() {
 
 bool StunMessage::Read(ByteBufferReader* buf) {
   // Keep a copy of the buffer data around for later verification.
-  buffer_.assign(buf->Data(), buf->Length());
+  buffer_.assign(reinterpret_cast<const char*>(buf->Data()), buf->Length());
 
   if (!buf->ReadUInt16(&type_)) {
     return false;
diff --git a/p2p/base/pseudo_tcp.cc b/p2p/base/pseudo_tcp.cc
index 9dec580b77..3aaa2ad065 100644
--- a/p2p/base/pseudo_tcp.cc
+++ b/p2p/base/pseudo_tcp.cc
@@ -1213,7 +1213,7 @@ void PseudoTcp::parseOptions(const char* data, uint32_t len) {
 
     // Content of this option.
     if (opt_len <= buf.Length()) {
-      applyOption(kind, buf.Data(), opt_len);
+      applyOption(kind, reinterpret_cast<const char*>(buf.Data()), opt_len);
       buf.Consume(opt_len);
     } else {
       RTC_LOG(LS_ERROR) << "Invalid option length received.";
diff --git a/rtc_base/byte_buffer.cc b/rtc_base/byte_buffer.cc
index 8c3595617c..121097bae9 100644
--- a/rtc_base/byte_buffer.cc
+++ b/rtc_base/byte_buffer.cc
@@ -139,10 +139,6 @@ bool ByteBufferReader::ReadBytes(rtc::ArrayView<uint8_t> val) {
   return ReadBytes(val.data(), val.size());
 }
 
-bool ByteBufferReader::ReadBytes(char* val, size_t len) {
-  return ReadBytes(reinterpret_cast<uint8_t*>(val), len);
-}
-
 // Private function supporting the other Read* functions.
 bool ByteBufferReader::ReadBytes(uint8_t* val, size_t len) {
   if (len > Length()) {
diff --git a/rtc_base/byte_buffer.h b/rtc_base/byte_buffer.h
index 9e169f221b..6df285ae6d 100644
--- a/rtc_base/byte_buffer.h
+++ b/rtc_base/byte_buffer.h
@@ -100,12 +100,6 @@ class ByteBufferWriterT {
   void WriteBytes(const uint8_t* val, size_t len) {
     WriteBytesInternal(reinterpret_cast<const value_type*>(val), len);
   }
-  // For backwards compatibility: Write an array of char
-  // TODO(bugs.webrtc.org/15665): Remove when users converted
-  [[deprecated("Use WriteString")]] void WriteBytes(const char* val,
-                                                    size_t len) {
-    WriteBytesInternal(reinterpret_cast<const value_type*>(val), len);
-  }
 
   // Reserves the given number of bytes and returns a value_type* that can be
   // written into. Useful for functions that require a value_type* buffer and
@@ -163,14 +157,10 @@ class ByteBufferReader {
   ByteBufferReader(const ByteBufferReader&) = delete;
   ByteBufferReader& operator=(const ByteBufferReader&) = delete;
 
-  // Returns start of unprocessed data.
-  // TODO(bugs.webrtc.org/15661): Deprecate and remove.
-  const char* Data() const {
-    return reinterpret_cast<const char*>(bytes_ + start_);
-  }
+  const uint8_t* Data() const { return bytes_ + start_; }
   // Returns number of unprocessed bytes.
   size_t Length() const { return end_ - start_; }
-  // Returns a view of the unprocessed data.
+  // Returns a view of the unprocessed data. Does not move current position.
   rtc::ArrayView<const uint8_t> DataView() const {
     return rtc::ArrayView<const uint8_t>(bytes_ + start_, end_ - start_);
   }
@@ -183,11 +173,8 @@ class ByteBufferReader {
   bool ReadUInt32(uint32_t* val);
   bool ReadUInt64(uint64_t* val);
   bool ReadUVarint(uint64_t* val);
+  // Copies the val.size() next bytes into val.data().
   bool ReadBytes(rtc::ArrayView<uint8_t> val);
-  // For backwards compatibility.
-  // TODO(bugs.webrtc.org/15661): Deprecate and remove.
-  [[deprecated("Read using ArrayView")]] bool ReadBytes(char* val, size_t len);
-
   // Appends next `len` bytes from the buffer to `val`. Returns false
   // if there is less than `len` bytes left.
   bool ReadString(std::string* val, size_t len);
diff --git a/rtc_base/server_socket_adapters.cc b/rtc_base/server_socket_adapters.cc
index 47c19cbed9..0bef752f1e 100644
--- a/rtc_base/server_socket_adapters.cc
+++ b/rtc_base/server_socket_adapters.cc
@@ -75,7 +75,9 @@ void AsyncSocksProxyServerSocket::ProcessInput(char* data, size_t* len) {
 
   // Consume parsed data
   *len = response.Length();
-  memmove(data, response.Data(), *len);
+  if (response.Length() > 0) {
+    memmove(data, response.DataView().data(), *len);
+  }
 }
 
 void AsyncSocksProxyServerSocket::DirectSend(const ByteBufferWriter& buf) {