xxxxxxxxxx
/* not valid */
._user-name {
}
/* not valid*/
.-user-name {
}
/* not valid */
.-user-name {
}
/* valid */
.1user-name {
}
/* not valid */
.@user-name {
}
/* valid */
.user@name {
}
/* valid */
._user10name {
}
/* valid */
.u {
}
xxxxxxxxxx
Uncheck Guild Install in the Installation tab and try again!
Answer source: https://www.reddit.com/r/Discord_Bots/comments/1e6r0ua/private_application_cannot_have_a_default/