diff --git a/htdocs/core/db/mysqli.class.php b/htdocs/core/db/mysqli.class.php
index 24ed1425f6b..526d43de0ab 100644
--- a/htdocs/core/db/mysqli.class.php
+++ b/htdocs/core/db/mysqli.class.php
@@ -857,6 +857,7 @@ class DoliDBMysqli extends DoliDB
      *	Return charset used to store data in current database (same result than using SELECT default_character_set_name FROM information_schema.SCHEMATA WHERE schema_name = "databasename";)
      *
      *	@return		string		Charset
+     *  @see getDefaultCollationDatabase
      */
     function getDefaultCharacterSetDatabase()
     {
@@ -867,7 +868,9 @@ class DoliDBMysqli extends DoliDB
             return $this->forcecharset;
         }
         $liste=$this->fetch_array($resql);
-        return $liste['Value'];
+        $tmpval = $liste['Value'];
+
+        return $tmpval;
     }
 
     /**
@@ -900,6 +903,7 @@ class DoliDBMysqli extends DoliDB
      *	Return collation used in current database
      *
      *	@return		string		Collation value
+     *  @see getDefaultCharacterSetDatabase
      */
     function getDefaultCollationDatabase()
     {
@@ -910,7 +914,9 @@ class DoliDBMysqli extends DoliDB
             return $this->forcecollate;
         }
         $liste=$this->fetch_array($resql);
-        return $liste['Value'];
+        $tmpval = $liste['Value'];
+
+        return $tmpval;
     }
 
     /**
diff --git a/htdocs/install/mysql/migration/repair.sql b/htdocs/install/mysql/migration/repair.sql
index f9ec23d4f69..95840f73cb8 100755
--- a/htdocs/install/mysql/migration/repair.sql
+++ b/htdocs/install/mysql/migration/repair.sql
@@ -13,12 +13,17 @@
 -- flush privileges;
 
 
--- Requests to change character set and collation of a varchar column.
--- utf8 and utf8_unicode_ci is recommended (or even better utf8mb4 and utf8mb4_unicode_ci with mysql 5.5.3+)
+-- Request to change default pagecode + colation of database
+-- ALTER DATABASE name_of_database CHARACTER SET utf8 COLLATE utf8_unicode_ci;
 
+-- Request to change default pagecode + colation of table
+-- ALTER TABLE name_of_table CONVERT TO CHARACTER SET utf8 COLLATE utf8_unicode_ci;
+
+-- Request to change character set and collation of a varchar column.
+-- utf8 and utf8_unicode_ci is recommended (or even better utf8mb4 and utf8mb4_unicode_ci with mysql 5.5.3+)
 -- ALTER TABLE llx_accounting_account MODIFY account_number VARCHAR(20) CHARACTER SET utf8;
 -- ALTER TABLE llx_accounting_account MODIFY account_number VARCHAR(20) COLLATE utf8_unicode_ci;
--- You can check with 'show full columns from llx_accounting_account';
+-- You can check with 'show full columns from mytablename';
 
 
 
diff --git a/htdocs/install/mysql/tables/llx_product_attribute.key.sql b/htdocs/install/mysql/tables/llx_product_attribute.key.sql
index 28d687dbdda..f107a855e61 100644
--- a/htdocs/install/mysql/tables/llx_product_attribute.key.sql
+++ b/htdocs/install/mysql/tables/llx_product_attribute.key.sql
@@ -16,4 +16,5 @@
 --
 -- ============================================================================
 
-ALTER TABLE llx_product_attribute ADD CONSTRAINT unique_ref UNIQUE (ref);
\ No newline at end of file
+ALTER TABLE llx_product_attribute ADD UNIQUE INDEX uk_product_attribute_ref (ref);
+
diff --git a/htdocs/install/step1.php b/htdocs/install/step1.php
index 9ad30fe5d7b..a0fdc22a015 100644
--- a/htdocs/install/step1.php
+++ b/htdocs/install/step1.php
@@ -312,8 +312,11 @@ if (! $error && $db->connected)
 // Define $defaultCharacterSet and $defaultDBSortingCollation
 if (! $error && $db->connected)
 {
-    if (!empty($db_create_database)) { // If we create database, we force default value
-    	$defaultCharacterSet=$db->forcecharset;
+    if (!empty($db_create_database))    // If we create database, we force default value
+    {
+        // Default values come from the database handler
+
+        $defaultCharacterSet=$db->forcecharset;
     	$defaultDBSortingCollation=$db->forcecollate;
     }
     else	// If already created, we take current value
@@ -322,6 +325,14 @@ if (! $error && $db->connected)
         $defaultDBSortingCollation=$db->getDefaultCollationDatabase();
     }
 
+    // Force to avoid utf8mb4 because index on field char 255 reach limit of 767 char for indexes (example with mysql 5.6.34 = mariadb 10.0.29)
+    // TODO Remove this when utf8mb4 is supported
+    if ($defaultCharacterSet == 'utf8mb4' || $defaultDBSortingCollation == 'utf8mb4_unicode_ci')
+    {
+        $defaultCharacterSet = 'utf8';
+        $defaultDBSortingCollation = 'utf8_unicode_ci';
+    }
+
     print '<input type="hidden" name="dolibarr_main_db_character_set" value="'.$defaultCharacterSet.'">';
     print '<input type="hidden" name="dolibarr_main_db_collation" value="'.$defaultDBSortingCollation.'">';
     $db_character_set=$defaultCharacterSet;