Why did Mexico owed money to France?

In the 1860s, Mexico, deeply indebted to European countries, faced a decision about whether to pay interest or continue spending on internal matters, such as education. As a result of the crisis, Mexico was unable to pay its debts, and France, Spain and Britain sent fleets to Veracruz to demand payment. Eventually, Spain and Britain withdrew, leaving France to invade and occupy Mexico. The French imposed Maximilian I as emperor in an attempt to secure their economic interests in the region.