How to insert '1001-01-01 00:00:00' into MariaDB when altering a table?

I created a table in HeidiSQL: CREATE TABLE publish_dt ( ID BIGINT(20) NOT NULL AUTO_INCREMENT, TS DATETIME NULL DEFAULT NULL, Text VARCHAR(50) NOT NULL COLLATE 'utf8mb4_unicode_ci', PRIMARY KEY (ID) USING BTREE ) COLLATE='utf8mb4_unicode_ci' ENGINE=InnoDB AUTO_INCREMENT=2 ; Then I insert some data into the table, e.g. with INSERT INTO publish_dt (Text) VALUES ('Hello') Then I want to change TS column to non-NULL with a default of '1001-01-01 00:00:00'. I tried to do this in HeidiSQL, it produces the following ALTER TABLE query: ALTER TABLE publish_dt CHANGE COLUMN TS TS DATETIME NOT NULL DEFAULT '1001-01-01 00:00:00' AFTER ID; However, when I try to save changes in HeidiSQL, I receive the following error from the DB: SQL Error (1265): Data truncated for column 'TS' at row 1 Could you, please, clarify why this error happens (I couldn't find the same case with DATETIME on the internet) and how to work it around? Reason for asking: MariaDB documentation says > MariaDB stores values that use the DATETIME data type in a format that > supports values between 1000-01-01 00:00:00.000000 and 9999-12-31 > 23:59:59.999999.