diff --git a/htdocs/install/mysql/migration/2.7.0-2.8.0.sql b/htdocs/install/mysql/migration/2.7.0-2.8.0.sql
index 4c13b052eb0..95aa1c32b4a 100755
--- a/htdocs/install/mysql/migration/2.7.0-2.8.0.sql
+++ b/htdocs/install/mysql/migration/2.7.0-2.8.0.sql
@@ -141,6 +141,9 @@ ALTER TABLE llx_projet_task DROP INDEX statut;
 ALTER TABLE llx_projet_task ADD INDEX idx_projet_task_fk_projet (fk_projet);
 ALTER TABLE llx_projet_task ADD INDEX idx_projet_task_fk_user_creat (fk_user_creat);
 ALTER TABLE llx_projet_task ADD INDEX idx_projet_task_fk_user_valid (fk_user_valid);
+-- V4.1 DELETE FROM llx_projet_task WHERE fk_projet NOT IN (SELECT rowid from llx_projet);
+-- V4.1 UPDATE llx_projet_task set fk_user_creat=NULL WHERE fk_user_creat IS NOT NULL AND fk_user_creat NOT IN (SELECT rowid from llx_user);
+-- V4.1 UPDATE llx_projet_task set fk_user_valid=NULL WHERE fk_user_valid IS NOT NULL AND fk_user_valid NOT IN (SELECT rowid from llx_user);
 ALTER TABLE llx_projet_task ADD CONSTRAINT fk_projet_task_fk_projet 	FOREIGN KEY (fk_projet) REFERENCES llx_projet (rowid);
 ALTER TABLE llx_projet_task ADD CONSTRAINT fk_projet_task_fk_user_creat FOREIGN KEY (fk_user_creat) REFERENCES llx_user (rowid);
 ALTER TABLE llx_projet_task ADD CONSTRAINT fk_projet_task_fk_user_valid FOREIGN KEY (fk_user_valid) REFERENCES llx_user (rowid);