Resolve "An extension failed to initialize. Can't open file: Extend.dat"
If you are a Microsoft Outlook user and uses it especially for email program then you might come across an error message as discussed below:
"An extension failed to initialize. Can't open file: extend.dat. The file may not exist, you may not have permission to open it, or it may be open in another program. Right-click the folder that contains the file, and then click Properties to check your permissions for the folder. You don't have appropriate permissions to perform this operation."
This error message is generally encountered:
- When user open new email
- Try to open out of assistant or
- Even when you close the program
 
Due to this situation user becomes unable to access their email after this error message in extend.dat file extension. And to use the email again user will have to resolve the problem soon. Here many users are unable to understand the exact meaning of extend.dat file. This file is used to cache extension built for outlook. The problem in this file can be resolved by either deleting it or renaming it. In this situation if you are unable to view hidden files then you will have to set your explorer window in order to view all those types of files.
Now to fix this issue at first you will have to make sure that Outlook is closed and not running. Here if you are viewing hidden file and folders then you will have to use Windows explorer to go to documents and settings and then to the folder with the error. After this click on the Local settings, then application data, then Microsoft and then finally click and go to Outlook folder. And here you will find extended.dat. Now from here you can either rename the file and then try to send a email.
OR, to do this just type the below mentioned line in Command prompt, but make sure that Outlook is closed.
del “%userprofile%\local settings\application data\microsoft\outlook\extend.dat”
In case above mentioned steps does not work then it is important to check the Windows registry as it can be corrupt or damaged due to which the extended.dat file extension is receiving error message. You can use third part FileCure Software. This software is capable enough to resolve the entire registry problem that is related to extended.dat file extension. Moreover it also enables Outlook to send or receive ne email.
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