CREATE TABLE project (
    id INTEGER NOT NULL AUTO_INCREMENT,
    created_at DATETIME NOT NULL,
    name VARCHAR(75) NOT NULL,
    description LONGTEXT NOT NULL,
    is_active TINYINT NOT NULL DEFAULT '1',
    PRIMARY KEY (id),
    INDEX(name, created_at)
)
ENGINE = INNODB;

CREATE TABLE role (
    id INTEGER NOT NULL,
    name VARCHAR(50) NOT NULL,
    description LONGTEXT NOT NULL,
    PRIMARY KEY (id)
)
ENGINE = INNODB;

CREATE TABLE organization (
    id INTEGER NOT NULL AUTO_INCREMENT,
    created_at DATETIME NOT NULL,
    name VARCHAR(100) NOT NULL,
    is_active TINYINT NOT NULL DEFAULT '1',
    PRIMARY KEY (id)
)
ENGINE = INNODB;

CREATE TABLE user (
    id INTEGER NOT NULL AUTO_INCREMENT,
    created_at DATETIME NOT NULL,
    role_id INTEGER NOT NULL,
    organization_id INTEGER NOT NULL,
    last_login_at DATETIME NOT NULL,
    last_ip_address VARCHAR(25) NOT NULL,   
    username VARCHAR(45) NOT NULL,
    password CHAR(32) NOT NULL,
    email_address VARCHAR(255) NOT NULL,
    first_name VARCHAR(45) NOT NULL,
    last_name VARCHAR(45) NOT NULL,
    address_1 VARCHAR(100) NOT NULL,
    address_2 VARCHAR(25) NULL,
    city VARCHAR(25) NOT NULL,
    state CHAR(2) NOT NULL,
    zip_code VARCHAR(10) NOT NULL,
    primary_phone_number VARCHAR(10) NOT NULL,
    secondary_phone_number VARCHAR(10) NOT NULL,
    is_primary_organization_contact TINYINT NOT NULL DEFAULT '0',
    is_active TINYINT NOT NULL DEFAULT '1',
    PRIMARY KEY (id),
    CONSTRAINT fk_user_role_id
        FOREIGN KEY (role_id)
            REFERENCES role (id)
            ON UPDATE RESTRICT
            ON DELETE RESTRICT, 
    CONSTRAINT fk_user_organization_id
        FOREIGN KEY (organization_id)
            REFERENCES organization (id)
            ON UPDATE RESTRICT
            ON DELETE RESTRICT
)
ENGINE = INNODB;

CREATE TABLE project_user (
    user_id INTEGER NOT NULL,
    project_id INTEGER NOT NULL,
    PRIMARY KEY (user_id, project_id),
    CONSTRAINT fk_project_user_user_id
        FOREIGN KEY (user_id)
            REFERENCES user (id)
            ON UPDATE RESTRICT
            ON DELETE CASCADE,
    CONSTRAINT fk_project_user_project_id
        FOREIGN KEY (project_id)
            REFERENCES project (id)
            ON UPDATE RESTRICT
            ON DELETE RESTRICT
)
ENGINE = INNODB;

CREATE TABLE ticket_category (
    id INTEGER NOT NULL AUTO_INCREMENT,
    name VARCHAR(20) NOT NULL,
    description LONGTEXT NOT NULL,
    PRIMARY KEY (id)
)
ENGINE = INNODB;

CREATE TABLE ticket_type (
    id INTEGER NOT NULL AUTO_INCREMENT,
    name VARCHAR(20) NOT NULL,
    description LONGTEXT NOT NULL,
    PRIMARY KEY (id)
)
ENGINE = INNODB;

CREATE TABLE ticket_status (
    id INTEGER NOT NULL AUTO_INCREMENT,
    name VARCHAR(20) NOT NULL,
    description LONGTEXT NOT NULL,
    PRIMARY KEY (id)
)
ENGINE = INNODB;
CREATE TABLE ticket (
    id INTEGER NOT NULL AUTO_INCREMENT,
    created_at DATETIME NOT NULL,
    project_id INTEGER NOT NULL,
    created_by INTEGER NOT NULL,
    submitted_by INTEGER NOT NULL,
    assigned_to INTEGER NULL,
    category_id INTEGER NOT NULL,
    type_id INTEGER NOT NULL,
    title VARCHAR(75) NOT NULL,
    description LONGTEXT NOT NULL,
    contact_type_id TINYINT NOT NULL,
    affects_all_clients TINYINT NOT NULL DEFAULT '0',
    is_billable TINYINT NOT NULL DEFAULT '1',
    esimated_hours DECIMAL(4, 1) NOT NULL DEFAULT '0',
    hours_worked DECIMAL (4, 1) NOT NULL DEFAULT '0',
    status_id TINYINT NOT NULL,
    PRIMARY KEY (id),
    CONSTRAINT fk_ticket_project_id
        FOREIGN KEY (project_id)
            REFERENCES project (id)
            ON UPDATE RESTRICT
            ON DELETE RESTRICT,
    CONSTRAINT fk_ticket_created_by
        FOREIGN KEY (created_by)
            REFERENCES user (id)
            ON UPDATE RESTRICT
            ON DELETE RESTRICT,
    CONSTRAINT fk_ticket_submitted_by
        FOREIGN KEY (submitted_by)
            REFERENCES user (id)
            ON UPDATE RESTRICT
            ON DELETE RESTRICT,
    CONSTRAINT fk_ticket_assigned_to
        FOREIGN KEY (assigned_to)
            REFERENCES user (id)
            ON UPDATE RESTRICT
            ON DELETE RESTRICT,
    CONSTRAINT fk_ticket_category_id
        FOREIGN KEY (category_id)
            REFERENCES ticket_category (id)
            ON UPDATE RESTRICT
            ON DELETE RESTRICT,
    CONSTRAINT fk_ticket_type_id
        FOREIGN KEY (type_id)
            REFERENCES ticket_type (id)
            ON UPDATE RESTRICT
            ON DELETE RESTRICT,
    CONSTRAINT fk_ticket_status_id
        FOREIGN KEY (status_id)
            REFERENCES ticket_status (id)
            ON UPDATE RESTRICT
            ON DELETE RESTRICT
)
ENGINE = INNODB;

CREATE TABLE ticket_time_entry (
    id INTEGER NOT NULL AUTO_INCREMENT,
    user_id INTEGER NOT NULL,
    ticket_id INTEGER NOT NULL,
    started_at DATETIME NOT NULL,
    ended_at DATETIME NOT NULL,
    PRIMARY KEY (id),
    CONSTRAINT fk_ticket_time_entry_user_id
        FOREIGN KEY (user_id)
            REFERENCES user (id)
            ON UPDATE RESTRICT
            ON DELETE RESTRICT,
    CONSTRAINT fk_ticket_time_entry_ticket_id
        FOREIGN KEY (ticket_id)
            REFERENCES ticket (id)
            ON UPDATE RESTRICT
            ON DELETE RESTRICT
)
ENGINE = INNODB;

The ticket table's create statement causes an error 150. I have no clue why. When I remove the ON DELETE RESTRICT statements from the table declaration, it works. Why is that?