我正在尝试将 Lucene 索引从 4.6 升级到 8.0.0。当我尝试使用以下方法升级工具时：
java -cp lucene-core.jar:lucene-backward-codecs.jar \
org.apache.lucene.index.IndexUpgrader -delete-prior-commits \
/scratch/***/workspaces/trunk/****/indexes/4.6/
脚本从4.6到5.5.5、5.5.5到6.6.6、6.6.6到都运行良好7.7.2。但是当我尝试从它升级7.7.2到8.0.0它时会抛出如下错误。
Exception in thread "main" org.apache.lucene.index.IndexFormatTooOldException: Format version is not supported (resource BufferedChecksumIndexInput(MMapIndexInput(path="/scratch/**/workspaces/trunk/**/indexes/4.6/sd/segments_9"))): This index was initially created with Lucene 6.x while the current version is 8.0.0 and Lucene only supports reading the current and previous major versions.. This version of Lucene only supports indexes created with release 7.0 and …