事故现场

首先安装了elasticsearch 7.13.3，然后卸载了，再安装elasticsearch 7.13.2，启动报错：

java.lang.IllegalStateException: cannot downgrade a node from version [7.13.3] to version [7.13.2]
	at org.elasticsearch.env.NodeMetadata.upgradeToCurrentVersion(NodeMetadata.java:83) ~[elasticsearch-7.13.2.jar:7.13.2]
	at org.elasticsearch.env.NodeEnvironment.loadNodeMetadata(NodeEnvironment.java:423) ~[elasticsearch-7.13.2.jar:7.13.2]
	at org.elasticsearch.env.NodeEnvironment.<init>(NodeEnvironment.java:320) ~[elasticsearch-7.13.2.jar:7.13.2]
	at org.elasticsearch.node.Node.<init>(Node.java:368) ~[elasticsearch-7.13.2.jar:7.13.2]
	at org.elasticsearch.node.Node.<init>(Node.java:278) ~[elasticsearch-7.13.2.jar:7.13.2]
	at org.elasticsearch.bootstrap.Bootstrap$5.<init>(Bootstrap.java:217) ~[elasticsearch-7.13.2.jar:7.13.2]
	at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:217) ~[elasticsearch-7.13.2.jar:7.13.2]
	at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:397) [elasticsearch-7.13.2.jar:7.13.2]
	at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:159) [elasticsearch-7.13.2.jar:7.13.2]
	at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:150) [elasticsearch-7.13.2.jar:7.13.2]
	at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:75) [elasticsearch-7.13.2.jar:7.13.2]
	at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:116) [elasticsearch-cli-7.13.2.jar:7.13.2]
	at org.elasticsearch.cli.Command.main(Command.java:79) [elasticsearch-cli-7.13.2.jar:7.13.2]
	at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:115) [elasticsearch-7.13.2.jar:7.13.2]
	at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:81) [elasticsearch-7.13.2.jar:7.13.2]

事故原因

卸载elasticsearch 7.13.3没有卸载干净，/var/lib/elasticsearch路径下残留了一些数据，需要同时删除；