구글클라우드에 가상컴퓨터로 서버를 돌리다 어느날 다시 열려니 

[07:07:24 ERROR]: Failed to start the minecraft server

java.nio.file.AccessDeniedException: ./world/session.lock

        at java.base/sun.nio.fs.UnixException.translateToIOException(UnixException.java:90) ~[?:?]

        at java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:106) ~[?:?]

        at java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:111) ~[?:?]

        at java.base/sun.nio.fs.UnixFileSystemProvider.newFileChannel(UnixFileSystemProvider.java:224) ~[?:?]

        at java.base/java.nio.channels.FileChannel.open(FileChannel.java:309) ~[?:?]

        at java.base/java.nio.channels.FileChannel.open(FileChannel.java:369) ~[?:?]

        at net.minecraft.util.DirectoryLock.create(DirectoryLock.java:23) ~[paper-1.21.5.jar:1.21.5-76-04ffca0]

        at net.minecraft.world.level.storage.LevelStorageSource$LevelStorageAccess.<init>(LevelStorageSource.java:436) ~[paper-1.21.5.jar:1.21.5-76-04ffca0]

        at net.minecraft.world.level.storage.LevelStorageSource.validateAndCreateAccess(LevelStorageSource.java:351) ~[paper-1.21.5.jar:1.21.5-76-04ffca0]

        at net.minecraft.server.Main.main(Main.java:184) ~[paper-1.21.5.jar:1.21.5-76-04ffca0]

        at io.papermc.paper.PaperBootstrap.boot(PaperBootstrap.java:21) ~[paper-1.21.5.jar:1.21.5-76-04ffca0]

        at org.bukkit.craftbukkit.Main.main(Main.java:243) ~[paper-1.21.5.jar:1.21.5-76-04ffca0]

        at io.papermc.paperclip.Paperclip.lambda$main$0(Paperclip.java:42) ~[app:?]

        at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]

위와 같은 에러가 나면서 안켜집니다. 무엇이 문제일까요? 

session.lock 파일도 지워봤는데 안되네요.