diff --git a/contrib/xml2/xpath.c b/contrib/xml2/xpath.c
index 1e5b71d9a02..0555294f234 100644
--- a/contrib/xml2/xpath.c
+++ b/contrib/xml2/xpath.c
@@ -74,8 +74,6 @@ pgxml_parser_init(PgXmlStrictness strictness)
 	/* Initialize libxml */
 	xmlInitParser();
 
-	xmlSubstituteEntitiesDefault(1);
-	xmlLoadExtDtdDefaultValue = 1;
 
 	return xmlerrcxt;
 }
@@ -425,8 +423,9 @@ pgxml_xpath(text *document, xmlChar *xpath, xpath_workspace *workspace)
 
 	PG_TRY();
 	{
-		workspace->doctree = xmlParseMemory((char *) VARDATA_ANY(document),
-											docsize);
+		workspace->doctree = xmlReadMemory((char *) VARDATA_ANY(document),
+										   docsize, NULL, NULL,
+										   XML_PARSE_NOENT);
 		if (workspace->doctree != NULL)
 		{
 			workspace->ctxt = xmlXPathNewContext(workspace->doctree);
@@ -719,7 +718,9 @@ xpath_table(PG_FUNCTION_ARGS)
 
 			/* Parse the document */
 			if (xmldoc)
-				doctree = xmlParseMemory(xmldoc, strlen(xmldoc));
+				doctree = xmlReadMemory(xmldoc, strlen(xmldoc),
+										NULL, NULL,
+										XML_PARSE_NOENT);
 			else				/* treat NULL as not well-formed */
 				doctree = NULL;
 
diff --git a/contrib/xml2/xslt_proc.c b/contrib/xml2/xslt_proc.c
index 2189bca86ff..f30a3a42c03 100644
--- a/contrib/xml2/xslt_proc.c
+++ b/contrib/xml2/xslt_proc.c
@@ -85,16 +85,18 @@ xslt_process(PG_FUNCTION_ARGS)
 		bool		xslt_sec_prefs_error;
 
 		/* Parse document */
-		doctree = xmlParseMemory((char *) VARDATA_ANY(doct),
-								 VARSIZE_ANY_EXHDR(doct));
+		doctree = xmlReadMemory((char *) VARDATA_ANY(doct),
+								VARSIZE_ANY_EXHDR(doct), NULL, NULL,
+								XML_PARSE_NOENT);
 
 		if (doctree == NULL)
 			xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
 						"error parsing XML document");
 
 		/* Same for stylesheet */
-		ssdoc = xmlParseMemory((char *) VARDATA_ANY(ssheet),
-							   VARSIZE_ANY_EXHDR(ssheet));
+		ssdoc = xmlReadMemory((char *) VARDATA_ANY(ssheet),
+							  VARSIZE_ANY_EXHDR(ssheet), NULL, NULL,
+							  XML_PARSE_NOENT);
 
 		if (ssdoc == NULL)
 			xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
diff --git a/gpcontrib/gp_stats_collector/Makefile b/gpcontrib/gp_stats_collector/Makefile
index 43255ca1955..b3228d2c45e 100644
--- a/gpcontrib/gp_stats_collector/Makefile
+++ b/gpcontrib/gp_stats_collector/Makefile
@@ -7,7 +7,7 @@ PROTO_BASES = gpsc_plan gpsc_metrics gpsc_set_service
 PROTO_OBJS  = $(patsubst %,src/protos/%.pb.o,$(PROTO_BASES))
 
 C_OBJS   = $(patsubst %.c,%.o,$(wildcard src/*.c src/*/*.c))
-CPP_OBJS = $(patsubst %.cpp,%.o,$(wildcard src/*.cpp src/*/*.cpp))
+CPP_OBJS = $(patsubst %.cpp,%.o,$(wildcard src/*.cpp src/log/*.cpp src/memory/*.cpp))
 OBJS     = $(C_OBJS) $(CPP_OBJS) $(PROTO_OBJS)
 
 PG_CXXFLAGS += -Werror -Wall -Wno-unused-but-set-variable -std=c++17 -Isrc/protos -Isrc -Iinclude -DGPBUILD
diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index 6d38a2d0de2..aafa6203b93 100644
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -65,6 +65,16 @@
 #if LIBXML_VERSION >= 20704
 #define HAVE_XMLSTRUCTUREDERRORCONTEXT 1
 #endif
+
+/*
+ * libxml2 2.12 decided to insert "const" into the error handler API.
+ */
+#if LIBXML_VERSION >= 21200
+#define PgXmlErrorPtr const xmlError *
+#else
+#define PgXmlErrorPtr xmlErrorPtr
+#endif
+
 #endif							/* USE_LIBXML */
 
 #include "access/htup_details.h"
@@ -121,7 +131,7 @@ struct PgXmlErrorContext
 
 static xmlParserInputPtr xmlPgEntityLoader(const char *URL, const char *ID,
 										   xmlParserCtxtPtr ctxt);
-static void xml_errorHandler(void *data, xmlErrorPtr error);
+static void xml_errorHandler(void *data, PgXmlErrorPtr error);
 static void xml_ereport_by_code(int level, int sqlcode,
 								const char *msg, int errcode);
 static void chopStringInfoNewlines(StringInfo str);
@@ -1762,7 +1772,7 @@ xml_ereport(PgXmlErrorContext *errcxt, int level, int sqlcode, const char *msg)
  * Error handler for libxml errors and warnings
  */
 static void
-xml_errorHandler(void *data, xmlErrorPtr error)
+xml_errorHandler(void *data, PgXmlErrorPtr error)
 {
 	PgXmlErrorContext *xmlerrcxt = (PgXmlErrorContext *) data;
 	xmlParserCtxtPtr ctxt = (xmlParserCtxtPtr) error->ctxt;
diff --git a/src/interfaces/libpq/fe-secure-openssl.c b/src/interfaces/libpq/fe-secure-openssl.c
index 5c6b317caa7..ccd886abb84 100644
--- a/src/interfaces/libpq/fe-secure-openssl.c
+++ b/src/interfaces/libpq/fe-secure-openssl.c
@@ -797,7 +797,6 @@ initialize_SSL(PGconn *conn)
 	bool		have_homedir;
 	bool		have_cert;
 	bool		have_rootcert;
-	EVP_PKEY   *pkey = NULL;
 
 	/*
 	 * We'll need the home directory if any of the relevant parameters are
@@ -1133,6 +1132,7 @@ initialize_SSL(PGconn *conn)
 			/* Colon, but not in second character, treat as engine:key */
 			char	   *engine_str = strdup(conn->sslkey);
 			char	   *engine_colon;
+			EVP_PKEY   *pkey;
 
 			if (engine_str == NULL)
 			{