I've encountered it, too. Here's my problem:

<el-col :span="14" class="userinfo">
    <el-dropdown trigger="hover">
        <span class="el-dropdown-link userinfo-inner" @click="logout"></span>
    </el-dropdown>
</el-col>

when I use the el-dropdown tag, I don't use el-dropdown-menu or even el-dropdown-item. Maybe it's because the page traverses the drop-down menu every time, but I don't write down the pull-down menu, so no matter what I do, I will declare forEach as null,. I just get rid of el-dropdown. I'm a beginner, and there are many holes, so I specifically register the reply in order to reply so that I can retrieve it later

<el-col :span="14" class="userinfo">
    <span class="el-dropdown-link userinfo-inner" @click="logout"></span>
</el-col>

generally this problem is caused by the fact that the variable in forEach is not an array.
output that variable in front of forEach and then debugger, to see what it is.
usually when I deal with forEach, I will judge

arr && arr.forEach(i => {});

// 
(arr || []).forEach(i => {});

this.menuItemsArray is not an array, but null

maybe there is something wrong with your assignment

the default value of menuItemsArray is null.

querySelectorAll to an array should not be null

has it been solved? what's the reason? I also encountered this problem in the project

Hello. Have I also encountered a solution?