原因：可能是文件过大，不能超过，因为PC端的设置为小于100M还有可能是自身网络不够稳定。
1、登陆。
2、进入以后我们看到里面的二维码，拿出手机扫描二维码，便可成功登陆。
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https://iknow-pic.cdn.bcebos.com/adaf2edda3cc7cd9d30a0e243501213fb80e9123"/>
3、登陆成功以后，出现一个微信聊天界面。选择一个微信好友。并选择右侧下面的文件添加按钮。
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https://iknow-pic.cdn.bcebos.com/b17eca8065380cd7df219810ad44ad345982810b"/>
4、点击以后，出现文件浏览选项，选择好要发送的文件即可。
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https://iknow-pic.cdn.bcebos.com/4610b912c8fcc3ce7339f2ce9e45d688d53f2055"/>
5、稍等片刻，即可发送成功。
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https://iknow-pic.cdn.bcebos.com/962bd40735fae6cdb38a919c03b30f2442a70f14"/>
注：是微信对上传文件大小的上限是不一样的。
网页版微信最大：20M
Windows版微信最大：25MB
MAC版微信最大：30MB