diff --git a/ed25519/src/seed.cpp b/ed25519/src/seed.cpp
index 2123cc56c..7d03a37a0 100644
--- a/ed25519/src/seed.cpp
+++ b/ed25519/src/seed.cpp
@@ -46,13 +46,13 @@ void ed25519_create_seed(unsigned char *seed) {
     FILE *f = fopen("/dev/urandom", "rb");
 
     if (f == NULL) {
-        throw boost::system::system_error(boost::system::error_code(errno, boost::system::generic_category()));
+        throw boost::system::system_error(boost::system::error_code(errno, boost::system::system_category()));
     }
 
     int read = fread(seed, 1, 32, f);
     if (read != 32) {
         fclose(f);
-        throw boost::system::system_error(boost::system::error_code(errno, boost::system::generic_category()));
+        throw boost::system::system_error(boost::system::error_code(errno, boost::system::system_category()));
     }
 
     fclose(f);
diff --git a/examples/client_test.cpp b/examples/client_test.cpp
index 6b0ca07dc..0a0d00884 100644
--- a/examples/client_test.cpp
+++ b/examples/client_test.cpp
@@ -205,21 +205,21 @@ int load_file(std::string const& filename, std::vector<char>& v
 	FILE* f = fopen(filename.c_str(), "rb");
 	if (f == NULL)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		return -1;
 	}
 
 	int r = fseek(f, 0, SEEK_END);
 	if (r != 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
 	long s = ftell(f);
 	if (s < 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -233,7 +233,7 @@ int load_file(std::string const& filename, std::vector<char>& v
 	r = fseek(f, 0, SEEK_SET);
 	if (r != 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -248,7 +248,7 @@ int load_file(std::string const& filename, std::vector<char>& v
 	r = fread(&v[0], 1, v.size(), f);
 	if (r < 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -758,7 +758,7 @@ std::vector<std::string> list_dir(std::string path
 	DIR* handle = opendir(path.c_str());
 	if (handle == 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		return ret;
 	}
 
diff --git a/examples/dump_torrent.cpp b/examples/dump_torrent.cpp
index ca85df9f6..fa1b155d0 100644
--- a/examples/dump_torrent.cpp
+++ b/examples/dump_torrent.cpp
@@ -44,21 +44,21 @@ int load_file(std::string const& filename, std::vector<char>& v
 	FILE* f = fopen(filename.c_str(), "rb");
 	if (f == NULL)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		return -1;
 	}
 
 	int r = fseek(f, 0, SEEK_END);
 	if (r != 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
 	long s = ftell(f);
 	if (s < 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -72,7 +72,7 @@ int load_file(std::string const& filename, std::vector<char>& v
 	r = fseek(f, 0, SEEK_SET);
 	if (r != 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -87,7 +87,7 @@ int load_file(std::string const& filename, std::vector<char>& v
 	r = fread(&v[0], 1, v.size(), f);
 	if (r < 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
diff --git a/examples/make_torrent.cpp b/examples/make_torrent.cpp
index 5af2aae8b..e441b1626 100644
--- a/examples/make_torrent.cpp
+++ b/examples/make_torrent.cpp
@@ -55,21 +55,21 @@ int load_file(std::string const& filename, std::vector<char>& v, libtorrent::err
 	FILE* f = fopen(filename.c_str(), "rb");
 	if (f == NULL)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		return -1;
 	}
 
 	int r = fseek(f, 0, SEEK_END);
 	if (r != 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
 	long s = ftell(f);
 	if (s < 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -83,7 +83,7 @@ int load_file(std::string const& filename, std::vector<char>& v, libtorrent::err
 	r = fseek(f, 0, SEEK_SET);
 	if (r != 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -98,7 +98,7 @@ int load_file(std::string const& filename, std::vector<char>& v, libtorrent::err
 	r = fread(&v[0], 1, v.size(), f);
 	if (r < 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
diff --git a/src/disk_buffer_pool.cpp b/src/disk_buffer_pool.cpp
index aeff5ddb4..725c0b4f9 100644
--- a/src/disk_buffer_pool.cpp
+++ b/src/disk_buffer_pool.cpp
@@ -549,7 +549,7 @@ namespace libtorrent
 			m_cache_fd = open(sett.get_str(settings_pack::mmap_cache).c_str(), O_RDWR | O_CREAT | O_EXLOCK | O_TRUNC, 0700);
 			if (m_cache_fd < 0)
 			{
-				ec.assign(errno, boost::system::generic_category());
+				ec.assign(errno, boost::system::system_category());
 			}
 			else
 			{
@@ -561,7 +561,7 @@ namespace libtorrent
 					, MAP_SHARED | MAP_NOCACHE, m_cache_fd, 0));
 				if (intptr_t(m_cache_pool) == -1)
 				{
-					ec.assign(errno, boost::system::generic_category());
+					ec.assign(errno, boost::system::system_category());
 
 					m_cache_pool = 0;
 					// attempt to make MacOS not flush this to disk, making close()
diff --git a/src/file.cpp b/src/file.cpp
index 695fcc71d..e6027e03e 100644
--- a/src/file.cpp
+++ b/src/file.cpp
@@ -393,7 +393,7 @@ namespace libtorrent
 			retval = ::stat(f.c_str(), &ret);
 		if (retval < 0)
 		{
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			return;
 		}
 
@@ -427,7 +427,7 @@ namespace libtorrent
 		if (::rename(f1.c_str(), f2.c_str()) < 0)
 #endif
 		{
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			return;
 		}
 	}
@@ -468,7 +468,7 @@ namespace libtorrent
 		std::string n = convert_to_native(f);
 		int ret = mkdir(n.c_str(), 0777);
 		if (ret < 0 && errno != EEXIST)
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 #endif
 	}
 
@@ -527,7 +527,7 @@ namespace libtorrent
 		if (errno != EMLINK || errno != EXDEV)
 		{
 			// some error happened, report up to the caller
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			return;
 		}
 
@@ -594,7 +594,7 @@ namespace libtorrent
 		// this only works on 10.5
 		copyfile_state_t state = copyfile_state_alloc();
 		if (copyfile(f1.c_str(), f2.c_str(), state, COPYFILE_ALL) < 0)
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 		copyfile_state_free(state);
 #else
 		std::string f1 = convert_to_native(inf);
@@ -603,7 +603,7 @@ namespace libtorrent
 		int infd = ::open(f1.c_str(), O_RDONLY);
 		if (infd < 0)
 		{
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			return;
 		}
 
@@ -617,7 +617,7 @@ namespace libtorrent
 		if (outfd < 0)
 		{
 			close(infd);
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			return;
 		}
 		char buffer[4096];
@@ -627,13 +627,13 @@ namespace libtorrent
 			if (num_read == 0) break;
 			if (num_read < 0)
 			{
-				ec.assign(errno, generic_category());
+				ec.assign(errno, system_category());
 				break;
 			}
 			int num_written = write(outfd, buffer, num_read);
 			if (num_written < num_read)
 			{
-				ec.assign(errno, generic_category());
+				ec.assign(errno, system_category());
 				break;
 			}
 			if (num_read < int(sizeof(buffer))) break;
@@ -1042,7 +1042,7 @@ namespace libtorrent
 		std::string const& f = convert_to_native(inf);
 		if (::remove(f.c_str()) < 0)
 		{
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			return;
 		}
 #endif // TORRENT_WINDOWS
@@ -1137,7 +1137,7 @@ namespace libtorrent
 		m_handle = opendir(p.c_str());
 		if (m_handle == 0)
 		{
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			m_done = true;
 			return;
 		}
@@ -1199,7 +1199,7 @@ namespace libtorrent
 		dirent* dummy;
 		if (readdir_r(m_handle, &m_dirent, &dummy) != 0)
 		{
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			m_done = true;
 		}
 		if (dummy == 0) m_done = true;
@@ -1447,7 +1447,7 @@ namespace libtorrent
 #endif
 		if (handle == -1)
 		{
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			TORRENT_ASSERT(ec);
 			return false;
 		}
@@ -1693,7 +1693,7 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 #ifdef TORRENT_WINDOWS
 				ec.assign(GetLastError(), system_category());
 #else
-				ec.assign(errno, generic_category());
+				ec.assign(errno, system_category());
 #endif
 				return -1;
 			}
@@ -1723,7 +1723,7 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 #ifdef TORRENT_WINDOWS
 				ec.assign(GetLastError(), system_category());
 #else
-				ec.assign(errno, generic_category());
+				ec.assign(errno, system_category());
 #endif
 				return -1;
 			}
@@ -1747,7 +1747,7 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 #else
 		if (lseek(fd, file_offset, SEEK_SET) < 0)
 		{
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			return -1;
 		}
 #endif
@@ -1760,7 +1760,7 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 #ifdef TORRENT_WINDOWS
 				ec.assign(GetLastError(), system_category());
 #else
-				ec.assign(errno, generic_category());
+				ec.assign(errno, system_category());
 #endif
 				return -1;
 			}
@@ -1786,7 +1786,7 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 #ifdef TORRENT_WINDOWS
 			ec = error_code(ERROR_INVALID_HANDLE, system_category());
 #else
-			ec = error_code(EBADF, generic_category());
+			ec = error_code(boost::system::errc::bad_file_descriptor, generic_category());
 #endif
 			return -1;
 		}
@@ -1834,7 +1834,7 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 #ifdef TORRENT_WINDOWS
 			ec = error_code(ERROR_INVALID_HANDLE, system_category());
 #else
-			ec = error_code(EBADF, generic_category());
+			ec = error_code(boost::system::errc::bad_file_descriptor, generic_category());
 #endif
 			return -1;
 		}
@@ -1878,7 +1878,7 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 				&& errno != EINVAL
 				&& errno != ENOSYS)
 			{
-				ec.assign(errno, generic_category());
+				ec.assign(errno, system_category());
 			}
 		}
 #endif
@@ -2073,7 +2073,7 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 		struct stat st;
 		if (fstat(native_handle(), &st) != 0)
 		{
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			return false;
 		}
 
@@ -2081,7 +2081,7 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 		// have the right size. We don't want to update
 		if (st.st_size != s && ftruncate(native_handle(), s) < 0)
 		{
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			return false;
 		}
 
@@ -2103,14 +2103,14 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 			{
 				if (errno != ENOSPC)
 				{
-					ec.assign(errno, generic_category());
+					ec.assign(errno, system_category());
 					return false;
 				}
 				// ok, let's try to allocate non contiguous space then
 				f.fst_flags = F_ALLOCATEALL;
 				if (fcntl(native_handle(), F_PREALLOCATE, &f) < 0)
 				{
-					ec.assign(errno, generic_category());
+					ec.assign(errno, system_category());
 					return false;
 				}
 			}
@@ -2123,7 +2123,7 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 			fl64.l_len = s;
 			if (fcntl(native_handle(), F_ALLOCSP64, &fl64) < 0)
 			{
-				ec.assign(errno, generic_category());
+				ec.assign(errno, system_category());
 				return false;
 			}
 
@@ -2143,7 +2143,7 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 			// filesystem does not support this operation
 			if (ret != 0 && ret != EINVAL)
 			{
-				ec.assign(ret, generic_category());
+				ec.assign(ret, system_category());
 				return false;
 			}
 #endif // TORRENT_HAS_FALLOCATE
@@ -2166,7 +2166,7 @@ typedef struct _FILE_ALLOCATED_RANGE_BUFFER {
 		struct stat fs;
 		if (fstat(native_handle(), &fs) != 0)
 		{
-			ec.assign(errno, generic_category());
+			ec.assign(errno, system_category());
 			return -1;
 		}
 		return fs.st_size;
diff --git a/src/torrent.cpp b/src/torrent.cpp
index d2d14a75a..3faf51a0a 100644
--- a/src/torrent.cpp
+++ b/src/torrent.cpp
@@ -976,7 +976,7 @@ namespace libtorrent
 		{
 			// failed
 			m_ses.alerts().emplace_alert<read_piece_alert>(
-				get_handle(), piece, error_code(boost::system::errc::operation_canceled, system_category()));
+				get_handle(), piece, error_code(boost::system::errc::operation_canceled, generic_category()));
 			return;
 		}
 
@@ -1202,7 +1202,7 @@ namespace libtorrent
 			update_gauge();
 		}
 
-		if (j->error.ec == error_code(boost::system::errc::not_enough_memory, generic_category()))
+		if (j->error.ec == boost::system::errc::not_enough_memory)
 		{
 			if (alerts().should_post<file_error_alert>())
 				alerts().emplace_alert<file_error_alert>(j->error.ec
@@ -5107,7 +5107,7 @@ namespace libtorrent
 			if (flags & torrent_handle::alert_when_available)
 			{
 				m_ses.alerts().emplace_alert<read_piece_alert>(
-					get_handle(), piece, error_code(boost::system::errc::operation_canceled, system_category()));
+					get_handle(), piece, error_code(boost::system::errc::operation_canceled, generic_category()));
 			}
 			return;
 		}
@@ -5243,7 +5243,7 @@ namespace libtorrent
 			{
 				// post an empty read_piece_alert to indicate it failed
 				alerts().emplace_alert<read_piece_alert>(
-					get_handle(), piece, error_code(boost::system::errc::operation_canceled, system_category()));
+					get_handle(), piece, error_code(boost::system::errc::operation_canceled, generic_category()));
 			}
 			if (has_picker()) m_picker->set_piece_priority(piece, 1);
 			m_time_critical_pieces.erase(i);
@@ -5260,7 +5260,7 @@ namespace libtorrent
 			{
 				// post an empty read_piece_alert to indicate it failed
 				m_ses.alerts().emplace_alert<read_piece_alert>(
-					get_handle(), i->piece, error_code(boost::system::errc::operation_canceled, system_category()));
+					get_handle(), i->piece, error_code(boost::system::errc::operation_canceled, generic_category()));
 			}
 			if (has_picker()) m_picker->set_piece_priority(i->piece, 1);
 			i = m_time_critical_pieces.erase(i);
@@ -5279,7 +5279,7 @@ namespace libtorrent
 				{
 					// post an empty read_piece_alert to indicate it failed
 					alerts().emplace_alert<read_piece_alert>(
-						get_handle(), i->piece, error_code(boost::system::errc::operation_canceled, system_category()));
+						get_handle(), i->piece, error_code(boost::system::errc::operation_canceled, generic_category()));
 				}
 				i = m_time_critical_pieces.erase(i);
 				continue;
@@ -5982,7 +5982,7 @@ namespace libtorrent
 #if BOOST_VERSION < 105400
 		if (alerts().should_post<torrent_error_alert>())
 			alerts().emplace_alert<torrent_error_alert>(get_handle()
-				, error_code(boost::system::errc::not_supported, system_category()), "[certificate]");
+				, error_code(boost::system::errc::not_supported, generic_category()), "[certificate]");
 #else
 		boost::asio::const_buffer certificate_buf(certificate.c_str(), certificate.size());
 
diff --git a/test/bdecode_benchmark.cpp b/test/bdecode_benchmark.cpp
index a15f61889..f2195e082 100644
--- a/test/bdecode_benchmark.cpp
+++ b/test/bdecode_benchmark.cpp
@@ -49,21 +49,21 @@ int load_file(std::string const& filename, std::vector<char>& v
 	FILE* f = fopen(filename.c_str(), "rb");
 	if (f == NULL)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		return -1;
 	}
 
 	int r = fseek(f, 0, SEEK_END);
 	if (r != 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
 	long s = ftell(f);
 	if (s < 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -77,7 +77,7 @@ int load_file(std::string const& filename, std::vector<char>& v
 	r = fseek(f, 0, SEEK_SET);
 	if (r != 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -92,7 +92,7 @@ int load_file(std::string const& filename, std::vector<char>& v
 	r = fread(&v[0], 1, v.size(), f);
 	if (r < 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
diff --git a/test/setup_transfer.cpp b/test/setup_transfer.cpp
index 2cc327ee9..96367e87d 100644
--- a/test/setup_transfer.cpp
+++ b/test/setup_transfer.cpp
@@ -170,21 +170,21 @@ int load_file(std::string const& filename, std::vector<char>& v, libtorrent::err
 	FILE* f = fopen(filename.c_str(), "rb");
 	if (f == NULL)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		return -1;
 	}
 
 	int r = fseek(f, 0, SEEK_END);
 	if (r != 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
 	long s = ftell(f);
 	if (s < 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -198,7 +198,7 @@ int load_file(std::string const& filename, std::vector<char>& v, libtorrent::err
 	r = fseek(f, 0, SEEK_SET);
 	if (r != 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -213,7 +213,7 @@ int load_file(std::string const& filename, std::vector<char>& v, libtorrent::err
 	r = fread(&v[0], 1, v.size(), f);
 	if (r < 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
diff --git a/tools/fuzz_torrent.cpp b/tools/fuzz_torrent.cpp
index ec4371b28..1a5bb9e61 100644
--- a/tools/fuzz_torrent.cpp
+++ b/tools/fuzz_torrent.cpp
@@ -293,21 +293,21 @@ int load_file(std::string const& filename, std::vector<char>& v
 	FILE* f = fopen(filename.c_str(), "rb");
 	if (f == NULL)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		return -1;
 	}
 
 	int r = fseek(f, 0, SEEK_END);
 	if (r != 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
 	long s = ftell(f);
 	if (s < 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -321,7 +321,7 @@ int load_file(std::string const& filename, std::vector<char>& v
 	r = fseek(f, 0, SEEK_SET);
 	if (r != 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}
@@ -336,7 +336,7 @@ int load_file(std::string const& filename, std::vector<char>& v
 	r = fread(&v[0], 1, v.size(), f);
 	if (r < 0)
 	{
-		ec.assign(errno, boost::system::generic_category());
+		ec.assign(errno, boost::system::system_category());
 		fclose(f);
 		return -1;
 	}