原貼地址：http://www.oracleblog.org/working-case/drop-user/
執行：
drop user abc cascade;
報錯：
VBO：無法刪除用戶。
ORA-01001 無效的遊標
ORA-00600: internal error code, arguments: [qmxiUnpPacked2], [121], [], [], [], [], [], []
這位朋友當前的用戶是sysdba用戶，應該不存在不能刪除自己的用戶的情況，而且從報錯的信息來看，ora－600屬於oracle自己的內部錯誤，和用戶操作關係不大。
開始還以爲這位朋友的oracle數據庫版本較低，但是經過諮詢，他是oracle9207版本，而且是windows 2003的系統平臺。想到windows下oracle的版本是9201的，9207肯定是升級上去的，於是懷疑在升級的過程中出了問題所致。
在metalink搜索了 drop user ora-00600，發現其中有一片文章（Doc ID：Note339070.1）說道：
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Subject: Drop user fails with ora-600 [qmxiUnpPacked2]
Doc ID: Note:339070.1 Type: PROBLEM
Last Revision Date: 07-DEC-2005 Status: PUBLISHED
In this Document
Symptoms
Cause
Solution
References
——————————————————————————–
Applies to:
Oracle Server – Enterprise Edition – Version: 9.2.0.7
This problem can occur on any platform.
Symptoms
ORA-600 [qmxiUnpPacked2] [121 being reported during a drop user on a new 9.2.0.7 database.
Cause
This is generally caused by an invalid upgrade from earlier release.
If a database is created with the DBCA at 9.2.0.7 and one of the "seed" databases are used (not the "New Database" option),
then this seed database is at 9.2.0.1.
Once the create database is complete it needs patching to 9.2.0.7
This error occurs due to XMLType data that has not been successfully upgraded from a previous version.
Solution
To implement the solution, please execute the following steps:
1)SQL> shutdown immediate
2)SQL> startup migrate
3)SQL> spool patch.log
4)SQL> @?/rdbms/admin/catpatch
5)SQL> spool off
References
Note 222876.1 - ORA-600 [qmxiUnpPacked2]
Errors
ORA-600[QMXIUNPPACKED2]
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而那位朋友在升級的時候，確實只運行了升級補丁（setup.exe），沒有進行後續的數據庫升級和 Internet Directory的升級。在該升級補丁的說明文檔中也寫明瞭後續要做的工作是：
● Upgrading Databases from Previous Releases Directly to Oracle9i Version 9.2.0.7.0
● Required Postinstallation Tasks
● Upgrading Oracle Internet Directory 9.2.0.x.x
至此，找到原因，問題解決。
題外話：大家升級的時候一定要清楚的知道自己在幹什麼，仔細閱讀升級文檔的每一處，除了升級過程，還有升級前的準備包括表空間，sga內存的檢查，升級後後續工作，等等。
