[Vuejs]-The <el-dropdown> is experiencing an issue and cannot be used

You’re using incorrect slot syntax

<el-dropdown-menu slot="dropdown">
 ...
</el-dropdown-menu>

Following the Element Plus documentation it should be:

<template v-slot:dropdown>
  <el-dropdown-menu>
  ...
  </el-dropdown-menu>
</template>

Or using shorthand:

<template #dropdown>
  <el-dropdown-menu>
  ...
  </el-dropdown-menu>
</template>

codepen example