diff --git a/htdocs/filefunc.inc.php b/htdocs/filefunc.inc.php
index 5be520d4f07..4c5cf0196ae 100644
--- a/htdocs/filefunc.inc.php
+++ b/htdocs/filefunc.inc.php
@@ -35,7 +35,7 @@ if (!defined('DOL_APPLICATION_TITLE')) {
 	define('DOL_APPLICATION_TITLE', 'Dolibarr');
 }
 if (!defined('DOL_VERSION')) {
-	define('DOL_VERSION', '20.0.0-beta'); // a.b.c-alpha, a.b.c-beta, a.b.c-rcX or a.b.c
+	define('DOL_VERSION', '21.0.0-alpha'); // a.b.c-alpha, a.b.c-beta, a.b.c-rcX or a.b.c
 }
 
 if (!defined('EURO')) {
diff --git a/htdocs/install/mysql/migration/20.0.0-21.0.0.sql b/htdocs/install/mysql/migration/20.0.0-21.0.0.sql
new file mode 100644
index 00000000000..136cbf9a4c2
--- /dev/null
+++ b/htdocs/install/mysql/migration/20.0.0-21.0.0.sql
@@ -0,0 +1,37 @@
+--
+-- This file is executed by calling /install/index.php page
+-- when current version is higher than the name of this file.
+-- Be carefull in the position of each SQL request.
+--
+-- To restrict request to Mysql version x.y minimum use -- VMYSQLx.y
+-- To restrict request to Pgsql version x.y minimum use -- VPGSQLx.y
+-- To rename a table:       ALTER TABLE llx_table RENAME TO llx_table_new; -- Note that "RENAME TO" is both compatible mysql/postgesql, not "RENAME" alone.
+-- To add a column:         ALTER TABLE llx_table ADD COLUMN newcol varchar(60) NOT NULL DEFAULT '0' AFTER existingcol;
+-- To rename a column:      ALTER TABLE llx_table CHANGE COLUMN oldname newname varchar(60);
+-- To drop a column:        ALTER TABLE llx_table DROP COLUMN oldname;
+-- To change type of field: ALTER TABLE llx_table MODIFY COLUMN name varchar(60);
+-- To drop a foreign key or constraint:   ALTER TABLE llx_table DROP FOREIGN KEY fk_name;
+-- To create a unique index:              ALTER TABLE llx_table ADD UNIQUE INDEX uk_table_field (field);
+-- To drop an index:        -- VMYSQL4.1 DROP INDEX nomindex ON llx_table;
+-- To drop an index:        -- VPGSQL8.2 DROP INDEX nomindex;
+-- To make pk to be auto increment (mysql):
+-- -- VMYSQL4.3 ALTER TABLE llx_table ADD PRIMARY KEY(rowid);
+-- -- VMYSQL4.3 ALTER TABLE llx_table CHANGE COLUMN rowid rowid INTEGER NOT NULL AUTO_INCREMENT;
+-- To make pk to be auto increment (postgres):
+-- -- VPGSQL8.2 CREATE SEQUENCE llx_table_rowid_seq OWNED BY llx_table.rowid;
+-- -- VPGSQL8.2 ALTER TABLE llx_table ADD PRIMARY KEY (rowid);
+-- -- VPGSQL8.2 ALTER TABLE llx_table ALTER COLUMN rowid SET DEFAULT nextval('llx_table_rowid_seq');
+-- -- VPGSQL8.2 SELECT setval('llx_table_rowid_seq', MAX(rowid)) FROM llx_table;
+-- To set a field as NULL:                     -- VMYSQL4.3 ALTER TABLE llx_table MODIFY COLUMN name varchar(60) NULL;
+-- To set a field as NULL:                     -- VPGSQL8.2 ALTER TABLE llx_table ALTER COLUMN name DROP NOT NULL;
+-- To set a field as NOT NULL:                 -- VMYSQL4.3 ALTER TABLE llx_table MODIFY COLUMN name varchar(60) NOT NULL;
+-- To set a field as NOT NULL:                 -- VPGSQL8.2 ALTER TABLE llx_table ALTER COLUMN name SET NOT NULL;
+-- To set a field as default NULL:             -- VPGSQL8.2 ALTER TABLE llx_table ALTER COLUMN name SET DEFAULT NULL;
+-- Note: fields with type BLOB/TEXT can't have default value.
+-- To rebuild sequence for postgresql after insert, by forcing id autoincrement fields:
+-- -- VPGSQL8.2 SELECT dol_util_rebuild_sequences();
+
+
+
+-- add billable attribute to project task
+ALTER TABLE llx_projet_task ADD COLUMN billable smallint DEFAULT 1;