In Islam, Hajj is one of the five pillars of the faith, and it is mandatory for Muslims who are physically and financially able to perform the pilgrimage at least once in their lifetime. However, there are some situations in which Hajj is not compulsory. Here are a few examples:

1. Health issues: If a person is not physically able to perform Hajj due to health reasons, such as a chronic illness or disability, they are not obligated to perform the pilgrimage.

2. Financial constraints: If a person is not financially able to afford the cost of Hajj, they are not obligated to perform the pilgrimage. However, if they can save enough money at a later time, they may perform Hajj later in life.

3. Personal circumstances: If a person has personal or family obligations that require their attention, such as caring for a sick family member or attending to other pressing matters, they may postpone or skip Hajj.

4. Travel restrictions: If a person lives in a country where travel to Saudi Arabia for Hajj is restricted, they may not be able to perform Hajj.

It is important to note that while Hajj is not compulsory in these situations, it is still considered a highly recommended act of worship. Muslims who are not obligated to perform Hajj may still choose to perform the pilgrimage as a voluntary act of worship if they are able to do so.