The reason is form-group
, form-row
, and form-inline
classes have been removed in Bootstrap 5:
Breaking change: Dropped form-specific layout classes for our grid system. Use our grid and utilities instead of .form-group, .form-row, or .form-inline.
https://getbootstrap.com/docs/5.0/migration/#forms
So Grid and Utilities are supposed to be used instead.
…but if you are looking for a quick solution, here’s how these classes were working in Bootstrap 4:
.form-group {
margin-bottom: 1rem;
}
.form-inline .form-control {
display: inline-block;
width: auto;
vertical-align: middle;
}
.form-row {
display: flex;
flex-wrap: wrap;
margin-right: -5px;
margin-left: -5px;
}
.form-row > .col {
padding-left: 5px;
padding-right: 5px;
}
label {
margin-bottom: 0.5rem;
}