diff --git a/htdocs/admin/agenda_xcal.php b/htdocs/admin/agenda_xcal.php
index 735cc8f268a..2b5cdd0e824 100644
--- a/htdocs/admin/agenda_xcal.php
+++ b/htdocs/admin/agenda_xcal.php
@@ -120,9 +120,8 @@ print "<br>";
 
 // Show message
 $message='';
-$slash = '/';
-$backslash = strtr($slash, '/', '\\');
-$urlwithouturlroot=preg_replace('/'.$backslash.DOL_URL_ROOT.'$/i','',$dolibarr_main_url_root);
+$pattern = str_replace('/','\/',DOL_URL_ROOT); // Add backslashes for regular expression
+$urlwithouturlroot=preg_replace('/'.$pattern.'$/i','',$dolibarr_main_url_root);
 $urlvcal='<a href="'.DOL_URL_ROOT.'/comm/action/agendaexport.php?format=vcal&exportkey='.($conf->global->MAIN_AGENDA_XCAL_EXPORTKEY?urlencode($conf->global->MAIN_AGENDA_XCAL_EXPORTKEY):'...').'" target="_blank">'.$urlwithouturlroot.DOL_URL_ROOT.'/comm/action/agendaexport.php?format=vcal&exportkey='.($conf->global->MAIN_AGENDA_XCAL_EXPORTKEY?urlencode($conf->global->MAIN_AGENDA_XCAL_EXPORTKEY):'KEYNOTDEFINED').'</a>';
 $message.=$langs->trans("WebCalUrlForVCalExport",'vcal',$urlvcal);
 $message.='<br>';
diff --git a/htdocs/admin/paybox.php b/htdocs/admin/paybox.php
index 4d1dbbec0a4..5d69bde5fc8 100644
--- a/htdocs/admin/paybox.php
+++ b/htdocs/admin/paybox.php
@@ -160,9 +160,8 @@ print '<br><br>';
 print '<u>'.$langs->trans("FollowingUrlAreAvailableToMakePayments").':</u><br>';
 // Should work with DOL_URL_ROOT='' or DOL_URL_ROOT='/dolibarr'
 $firstpart=$dolibarr_main_url_root;
-$slash = '/';
-$backslash = strtr($slash, '/', '\\');
-$regex='/'.$backslash.DOL_URL_ROOT.'$/i';
+$pattern = str_replace('/','\/',DOL_URL_ROOT); // Add backslashes for regular expression
+$regex='/'.$pattern.'$/i';
 $firstpart=preg_replace($regex,'',$firstpart);
 print '<br>';
 print img_picto('','puce.png').' '.$langs->trans("ToOfferALinkForOnlinePaymentOnFreeAmount",$servicename).':<br>';
diff --git a/htdocs/admin/webcalendar.php b/htdocs/admin/webcalendar.php
index 9918a344c18..e1790a6b50e 100644
--- a/htdocs/admin/webcalendar.php
+++ b/htdocs/admin/webcalendar.php
@@ -313,9 +313,8 @@ print "<br>";
 
 // Show message
 $message='';
-$slash = '/';
-$backslash = strtr($slash, '/', '\\');
-$urlwithouturlroot=preg_replace('/'.$backslash.DOL_URL_ROOT.'$/i','',$dolibarr_main_url_root);
+$pattern = str_replace('/','\/',DOL_URL_ROOT); // Add backslashes for regular expression
+$urlwithouturlroot=preg_replace('/'.$pattern.'$/i','',$dolibarr_main_url_root);
 $urlvcal='<a href="'.DOL_URL_ROOT.'/webcal/webcalexport.php?format=vcal&exportkey='.$conf->global->PHPWEBCALENDAR_PASSWORD_VCALEXPORT.'" target="_blank">'.$urlwithouturlroot.DOL_URL_ROOT.'/webcal/webcalexport.php?format=vcal&exportkey='.$conf->global->PHPWEBCALENDAR_PASSWORD_VCALEXPORT.'</a>';
 $message.=$langs->trans("WebCalUrlForVCalExport",'vcal',$urlvcal);
 $message.='<br>';
diff --git a/htdocs/admin/webservices.php b/htdocs/admin/webservices.php
index 55795db4524..75734829918 100644
--- a/htdocs/admin/webservices.php
+++ b/htdocs/admin/webservices.php
@@ -92,9 +92,8 @@ print '<br><br>';
 
 // Should work with DOL_URL_ROOT='' or DOL_URL_ROOT='/dolibarr'
 $firstpart=$dolibarr_main_url_root;
-$slash = '/';
-$backslash = strtr($slash, '/', '\\');
-$regex='/'.$backslash.DOL_URL_ROOT.'$/i';
+$pattern = str_replace('/','\/',DOL_URL_ROOT); // Add backslashes for regular expression
+$regex='/'.$pattern.'$/i';
 $firstpart=preg_replace($regex,'',$firstpart);
 
 print '<u>'.$langs->trans("WSDLCanBeDownloadedHere").':</u><br>';
diff --git a/htdocs/categories/categorie.class.php b/htdocs/categories/categorie.class.php
index 31744796bfe..a9fd66fa19a 100644
--- a/htdocs/categories/categorie.class.php
+++ b/htdocs/categories/categorie.class.php
@@ -612,7 +612,7 @@ class Categorie
 			$this->cats[$id_categ]['fulllabel']=$this->cats[$id_categ]['label'];
 		}
 		// We count number of _ to have level
-		$this->cats[$id_categ]['level']=strlen(eregi_replace('[^_]','',$this->cats[$id_categ]['fullpath']));
+		$this->cats[$id_categ]['level']=strlen(preg_replace('/[^_]/i','',$this->cats[$id_categ]['fullpath']));
 
 		// Process all childs on several levels of this category
 		$protection++;
@@ -1059,9 +1059,9 @@ class Categorie
 
 					// On determine nom du fichier vignette
 					$photo_vignette='';
-					if (eregi('(\.jpg|\.bmp|\.gif|\.png|\.tiff)$',$photo,$regs))
+					if (preg_match('/(\.jpg|\.bmp|\.gif|\.png|\.tiff)$/i',$photo,$regs))
 					{
-						$photo_vignette=eregi_replace($regs[0],'',$photo).'_small'.$regs[0];
+						$photo_vignette=preg_replace('/'.$regs[0].'/i','',$photo).'_small'.$regs[0];
 					}
 
 					// Objet
@@ -1091,15 +1091,16 @@ class Categorie
 	{
 		$dir = dirname($file).'/'; // Chemin du dossier contenant l'image d'origine
 		$dirthumb = $dir.'/thumbs/'; // Chemin du dossier contenant la vignette
-		$filename = eregi_replace($dir,'',$file); // Nom du fichier
+		$dir = str_replace('/','\/',$dir); // Add backslashes for regular expression
+		$filename = preg_replace('/'.$dir.'/i','',$file); // Nom du fichier
 
 		// On efface l'image d'origine
 		dol_delete_file($file,1);
 
 		// Si elle existe, on efface la vignette
-		if (eregi('(\.jpg|\.bmp|\.gif|\.png|\.tiff)$',$filename,$regs))
+		if (preg_match('/(\.jpg|\.bmp|\.gif|\.png|\.tiff)$/i',$filename,$regs))
 		{
-			$photo_vignette=eregi_replace($regs[0],'',$filename).'_small'.$regs[0];
+			$photo_vignette=preg_replace('/'.$regs[0].'/i','',$filename).'_small'.$regs[0];
 			if (file_exists($dirthumb.$photo_vignette))
 			{
 				dol_delete_file($dirthumb.$photo_vignette,1);