Outlook Sending Error - One or More Parameter Values are Not Valid

Error Scenario: Sometimes while sending an email or even addressing it, I get a message "Could not complete the operation. One or more parameter values are not valid". This issue happens with every fourth or fifth e-mail.

Error Message: “Could not complete the operation. One or more parameter values are not valid.”

Invalid parameter error in Outlook typically occurs when users try to address or send an email to someone and suddenly he/she gets above given error message in Outlook. The reason behind this error is corruption in “Auto-Complete” list.

Note: One or more parameters are not valid, Outlook error can also arise when you are dealing with meeting request, task (assign tasks to anyone) and while saving a new contact.

How to Clear Auto-Complete Cache to Resolve Parameter Value Error in MS-Outlook?

Outlook invalid parameter error is quite similar to other send/receive errors. But to solve this error, you have to deal with Auto-Complete List. As we have already discussed in the above section, this error raise due to the corrupt Auto-Complete List so to fix this issue user have to clear the names of his auto-complete list in Outlook. It's all about clearing the cache from the Auto Complete list. There are two ways to fix the MS Outlook invalid parameter error:

One by One: In this mode, you have to remove each email address from the Auto Complete list (one by one). Directly type the first letter of name in the address bar in new mail and name will automatically appear. Just move mouse on it and delete it.

Empty Auto Complete List: Removing a all the email address one by one is a tedious job, so to complete this task and resolve the invalid parameter error in Outlook just follow the given instructions;

  • Open Microsoft Outlook and click on "File" menu.

click on file Outlook 2010

  • From the "File" menu, make a click on "Option" button.

option in Outlook 2010

  • In this new window, go to the "Mail" option from the drop down menu.

mail outlook 2010

  • Click on the "Empty Auto-Complete List" button under the "Send Messages" section.

empty auto complete list

  • Finally click "Yes" to empty the Auto-complete list.

ok button

Workaround to clear the Auto-Complete Cache

With the help of “outlook.exe /cleanautocompletecache”, this task can be easily done. But to use this method, your Outlook must be completely closed.

Follow the given steps, if you encounter “parameters are not valid Outlook” error in Outlook:

  • Press Windows+R and open the “Run”.

run in Windows 7

  • Type the “outlook.exe /cleanautocompletecache” and click on “Ok” button.

clean auto complete cache

If still you are facing same error while working with Outlook, then you can switch to an utility known as "PST File Recovery". Because it is efficient enough to fix almost all the error issues of Outlook. It can retrieve corrupt data of Outlook data file in a healthy format.