Server Tomcat v8.5 Server at localhost was unable to start within 45 seconds. If the server requires more time, try increasing the timeout in the server editor.

Server Tomcat v9.0 Server at localhost was unable to start within 45 seconds. If the server requires more time, try increasing the timeout in the server editor.

这个错误是指服务器超时了。
两种方案吧。
先试试第一个：
https://blog.csdn.net/ancientear/article/details/86985395
用这个方法清空项目虚拟目录里的文件，然后重新运行程序

第二个方法：

步骤1->【Window】->【Show View】 -> 【Servers】

步骤2->双击【Servers】

步骤3 ->打开界面上的timeouts ，将45改成较大的数值即可