diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index 2b987ec1cbd..af29858c7bb 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -630,14 +630,14 @@ function dol_syslog($message, $level = LOG_INFO, $ident = 0, $suffixinfilename='
 		if ($level > $conf->global->SYSLOG_LEVEL) return;
 
 		// If adding log inside HTML page is required
-		if (! empty($_REQUEST['logtohtml']) && ! empty($conf->global->MAIN_LOGTOHTML))
+		if (! empty($_REQUEST['logtohtml']) && (! empty($conf->global->MAIN_ENABLE_LOG_TO_HTML) || ! empty($conf->global->MAIN_LOGTOHTML)))   // MAIN_LOGTOHTML kept for backward compatibility
 		{
 			$conf->logbuffer[] = dol_print_date(time(),"%Y-%m-%d %H:%M:%S")." ".$message;
 		}
 
-		//TODO: Remove this. MAIN_ENABLE_LOG_HTML should be deprecated and use a log handler dedicated to HTML output
+		//TODO: Remove this. MAIN_ENABLE_LOG_INLINE_HTML should be deprecated and use a log handler dedicated to HTML output
 		// If enable html log tag enabled and url parameter log defined, we show output log on HTML comments
-		if (! empty($conf->global->MAIN_ENABLE_LOG_HTML) && ! empty($_GET["log"]))
+		if (! empty($conf->global->MAIN_ENABLE_LOG_INLINE_HTML) && ! empty($_GET["log"]))
 		{
 			print "\n\n<!-- Log start\n";
 			print $message."\n";
diff --git a/htdocs/install/inc.php b/htdocs/install/inc.php
index c5ebc33c56e..9bc7363b931 100644
--- a/htdocs/install/inc.php
+++ b/htdocs/install/inc.php
@@ -127,7 +127,7 @@ if (! defined('DONOTLOADCONF') && file_exists($conffile) && filesize($conffile)
         $includeconferror='ErrorBadFormatForConfFile';
     }
 }
-$conf->global->MAIN_LOGTOHTML = 1;
+$conf->global->MAIN_ENABLE_LOG_TO_HTML = 1;
 
 // Define prefix
 if (! isset($dolibarr_main_db_prefix) || ! $dolibarr_main_db_prefix) $dolibarr_main_db_prefix='llx_';
diff --git a/htdocs/install/mysql/data/llx_const.sql b/htdocs/install/mysql/data/llx_const.sql
index 95dfb2683f9..90c0e612c36 100644
--- a/htdocs/install/mysql/data/llx_const.sql
+++ b/htdocs/install/mysql/data/llx_const.sql
@@ -34,6 +34,7 @@
 insert into llx_const (name, value, type, note, visible, entity) values ('MAIN_NOT_INSTALLED','1','chaine','Setup is running',1,0);
 insert into llx_const (name, value, type, note, visible, entity) values ('MAIN_FEATURES_LEVEL','0','chaine','Level of features to show: -1=stable+deprecated, 0=stable only (default), 1=stable+experimental, 2=stable+experimental+development',1,0);
 insert into llx_const (name, value, type, note, visible, entity) values ('MAILING_LIMIT_SENDBYWEB','25','chaine','Number of targets to defined packet size when sending mass email',1,0);
+insert into llx_const (name, value, type, note, visible, entity) values ('MAIN_ENABLE_LOG_TO_HTML','0','chaine','If this option is set to 1, it is possible to see log output at end of HTML sources by adding paramater logtohtml=1 on URL',1,0);
 
 -- Hidden and common to all entities
 insert into llx_const (name, value, type, note, visible, entity) values ('SYSLOG_HANDLERS','["mod_syslog_file"]','chaine','Which logger to use',0,0);
diff --git a/htdocs/install/mysql/migration/3.8.0-3.9.0.sql b/htdocs/install/mysql/migration/3.8.0-3.9.0.sql
index 16cbb13a57d..9d77a87fd7c 100755
--- a/htdocs/install/mysql/migration/3.8.0-3.9.0.sql
+++ b/htdocs/install/mysql/migration/3.8.0-3.9.0.sql
@@ -22,6 +22,9 @@
 -- -- VMYSQL4.1 DELETE FROM llx_usergroup_user      WHERE fk_usergroup NOT IN (SELECT rowid from llx_usergroup);
 
 
+insert into llx_const (name, value, type, note, visible, entity) values ('MAIN_ENABLE_LOG_TO_HTML','0','chaine','If this option is set to 1, it is possible to see log output at end of HTML sources by adding paramater logtohtml=1 on URL',1,0);
+
+
 -- Was done into a 3.8 fix, so we must do it also in 3.9 
 ALTER TABLE llx_don ADD COLUMN fk_country integer NOT NULL DEFAULT 0 after country;