One of the approaches to represent a ’’1’’ or ’’0’’ in a bubble lattice device is by the presence or absence of a Bloch line (BL) pair inside the domain wall. In garnet films with a properly prepared exchange coupled layer, a method has been found by which a bubble with no BL’s can be controllably switched to a bubble with one pair of BL’s and vice versa. The method involves using a local in‐plane magnetic field and a critical domain wall velocity. A model to explain the mechanism is proposed. Both types of bubbles are stable in the film as long as the wall velocity is kept below a certain critical value. Beyond the critical velocity, only bubbles with no BL’s are stable. The latter mechanism can be used to switch a bubble with one pair of BL’s back to one with no BL’s.