sequelize - Cannot add foreign key constraint

This is common type error mainly occurs because of

1. When the primary key data type and the foreign key data type did not matched

return sequelize.define('RefreshToken', {    userId: {      type: DataTypes.INTEGER(11), // The data type defined here and       references: {        model: 'Users',        key: 'idUsers'      }    }, return sequelize.define('Users', {    idUsers: {      type: DataTypes.INTEGER(11),  // This data type should be the same    },

2. When the referenced key is not a primary or unique key.

You can not have two primary keys, so other referenced keys should be defined unique. unique:true

 return sequelize.define('Users', {    idUsers: {      primaryKey: true      },    mail: {      type: DataTypes.STRING(45),      allowNull: false,      primaryKey: true   // You should change this to 'unique:true'. you cant hv two primary keys in one table.     }

I see two issues:

No table should contain two primary keys and userId shouldn't be in integer it should be a UUID.

I had a foreign key set to INT and it gave me error:

Unhandled rejection SequelizeDatabaseError: foreign key constraint "constraint_name_here" cannot be implemented

Try changing:

userId: {  type: DataTypes.INTEGER(11),  allowNull: false,  primaryKey: true,  references: {    model: 'Users',    key: 'idUsers'  }},

To

userId: {  type: DataTypes.UUID,  allowNull: false,  foreignKey: true,  references: {    model: 'Users',    key: 'idUsers'  }},