*** a/src/backend/utils/fmgr/dfmgr.c
--- b/src/backend/utils/fmgr/dfmgr.c
***************
*** 19,28 ****
--- 19,29 ----
  #ifndef WIN32_ONLY_COMPILER
  #include "dynloader.h"
  #else
  #include "port/dynloader/win32.h"
  #endif
+ #include "lib/stringinfo.h"
  #include "miscadmin.h"
  #include "utils/dynamic_loader.h"
  #include "utils/hsearch.h"
  
  
*************** PGFunction
*** 163,172 ****
--- 164,213 ----
  lookup_external_function(void *filehandle, char *funcname)
  {
  	return (PGFunction) pg_dlsym(filehandle, funcname);
  }
  
+ /*
+  * Detailed error report when module incompatibility is detected.
+  */
+ 
+ #define MAGIC_FIELD_TEST(field) do { \
+ 	if (srv->field != mod->field) { \
+ 		if (det->len) \
+ 			appendStringInfo(det, ", "); \
+ 		appendStringInfo(det, "%s: %d != %d", #field, mod->field, srv->field); \
+ 	} \
+ } while (0)
+ 
+ static void
+ module_incompat_error(const Pg_magic_struct *mod, const Pg_magic_struct *srv, const char *libname)
+ {
+ 	StringInfo det;
+ 
+ 	if (mod->version != srv->version)
+ 		ereport(ERROR,
+ 		 (errmsg("incompatible library \"%s\": version mismatch",
+ 				 libname),
+ 		  errdetail("Server is version %d.%d, library is version %d.%d.",
+ 					srv->version / 100,
+ 					srv->version % 100,
+ 					mod->version / 100,
+ 					mod->version % 100)));
+ 
+ 	det = makeStringInfo();
+ 
+ 	MAGIC_FIELD_TEST(funcmaxargs);
+ 	MAGIC_FIELD_TEST(indexmaxkeys);
+ 	MAGIC_FIELD_TEST(namedatalen);
+ 	MAGIC_FIELD_TEST(float4byval);
+ 	MAGIC_FIELD_TEST(float8byval);
+ 
+ 	ereport(ERROR,
+ 	 (errmsg("incompatible library \"%s\": magic block mismatch: %s",
+ 			 libname, det->data)));
+ }
+ #undef MAGIC_FIELD_TEST
  
  /*
   * Load the specified dynamic-link library file, unless it already is
   * loaded.	Return the pg_dl* handle for the file.
   *
*************** internal_load_library(const char *libnam
*** 255,281 ****
  
  				/* try to unlink library */
  				pg_dlclose(file_scanner->handle);
  				free((char *) file_scanner);
  
! 				/*
! 				 * Report suitable error.  It's probably not worth writing a
! 				 * separate error message for each field; only the most common
! 				 * case of wrong major version gets its own message.
! 				 */
! 				if (module_magic_data.version != magic_data.version)
! 					ereport(ERROR,
! 					 (errmsg("incompatible library \"%s\": version mismatch",
! 							 libname),
! 					  errdetail("Server is version %d.%d, library is version %d.%d.",
! 								magic_data.version / 100,
! 								magic_data.version % 100,
! 								module_magic_data.version / 100,
! 								module_magic_data.version % 100)));
! 				ereport(ERROR,
! 				 (errmsg("incompatible library \"%s\": magic block mismatch",
! 						 libname)));
  			}
  		}
  		else
  		{
  			/* try to unlink library */
--- 296,306 ----
  
  				/* try to unlink library */
  				pg_dlclose(file_scanner->handle);
  				free((char *) file_scanner);
  
! 				module_incompat_error(&module_magic_data, &magic_data, libname);
  			}
  		}
  		else
  		{
  			/* try to unlink library */