Dealing With “-1605 0xfffff9bb Jet_errkeyduplicate” Exchange Server Error

By Author: Split Tool
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MS Exchange Server is the most commonly used application in almost all the organizations. Exchange's major features consist of electronic email, calendaring, contacts, tasks, etc. and it provides support for mobile and web-based access to information with reliable data storage. Regular use of Exchange Server gets prone to inevitable corruption issues and you just can't help it but use Exchange disaster recovery tool in such times.
When Exchange database gets corrupt or damaged, you start getting Jet errors once you try to access the database. This behavior of Exchange Server database leads to significant data loss and requires immediate action for speedy Exchange disaster recovery.
The Jet errors generally occur when Exchange Server database gets damaged beyond repair capabilities of the Eseutil.exe and other EDB Recovery Tool. Many Jet errors are irreparable and one needs efficient Exchange disaster recovery software to recover corrupt Exchange database file.
For instance consider a practical scenario, when you may receive the below Jet error while working on Exchange Server or trying to repair the database ...
... using ESEUTIL utility:
-1605 0xFFFFF9BB JET_errKeyDuplicate Illegal duplicate key 4294965691
When the above error message is encountered, you can't continue using the Exchange Server database .EDB file. This error indicates that EDB file is severely damaged and thus immediate recovery of corrupted database is required.
There is an inbuilt utility provided by MS Exchange Server called ESEUTIL.exe, which handles database inconsistency and corruption issues. But this utility generally fails when degree of corruption is high and this particular error is quite complicated and can't be fixed using Eseutil.exe tool. If you keep running the Eseutil.exe tool after receiving this error message, it may cause a bigger headache, more loss of data. Or one can say it would simply aggravate the problem rather than alleviating it.
Actually what happens is when you run the Eseutil.exe, changes are not committed to Exchange Server Information Store or database, but the program modifies the database without displaying any sort of prior information. It can apply changes to database even if it shows that database is not repairable.
Therefore, it's always advisable to keep an absolute backup which is very much helpful in times of Exchange Server disaster. If you have valid and updated backup, you can easily restore your database from the backup and save your time and data. However, if the backup is either damaged or not updated, then you might get trapped and problem becomes more severe. But one should not worry when there is Exchange disaster recovery tool available as third party professional utility. It's an effective and powerful tool that systematically scans the damaged EDB file using advanced scanning techniques and extract damaged data from it.