The plugin generated 2 characters of unexpected output during activation.
I developed a plug-in myself, and the following error occurred when activating it: The plug-in generated 2 characters of […]
自己开发的插件，激活时出现以下错误：
The plugin generated 2 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.
后来发现，在两个php文件的开头各有一个空格，删掉之后，就没事了。
