[Resolved] Could not Complete the Operation One or More Parameters are Invalid Outlook Error

Most of the Microsoft Outlook users encounter Outlook error one or more parameters are not valid while sending an email, assigning a task, or saving new contact. And suddenly an error message get pop-up on their screen stated: “Could not complete the operation. One or more parameter values are not valid” error in MS Outlook.”

If you are also experiencing the same issue, then read the blog thoroughly to get an efficient solution for the same. At the beginning of the article, we have mentioned the root cause for the Microsoft Outlook could not complete the operation one or more parameters are not valid.

Main Cause: The primary reason behind this error that if there is corruption in the Auto-Complete list.

Well, the best and most effective solution to fix this error is by clearing the Auto-Complete list. So, we have mentioned some of the efficient ways to delete the auto-complete list.

How to Fix Outlook Error One or More Parameters Are Not Valid?

There are different techniques to clear the Auto-complete list in Outlook 2016, 2013, 2010, 2007, 2003, etc.

Trick 1:Clear Each Email Address Individually

You just need to remove each email address one by one from the Auto-complete list. This method is applicable in all versions of Outlook. Look at the steps required to do:

1: Type the first letter of the name in the address bar when creating a new email.

2: The recipient’s name will automatically appear in the address bar, move the mouse cursor over it to delete the email address.

Trick 2: Empty the All Auto-Complete List

Another method to clear the Auto-complete list is to empty the entire auto-complete list in Outlook. Follow the below steps to do the same:

1. Open MS Outlook application.
2. Go to the File tab and click Options.
3. Now, select Mail and scroll to the Send Messages section.
4. Click on the Empty Auto-Complete icon.
5. A notification will appear on the screen confirming the same. Click Yes to empty the list.

Once done with these steps, try to send an email from your Outlook account to check the Outlook error However, if you still encounter the one or more parameters values are not valid error in Outlook then you have to clear the cache of the autocomplete list.

To clear cache of the auto-complete list:

1: Open the Run command and type the following command.
Outlook.exe / cleanautocompletecache

By this way, you will definitely fix this issue but in case Outlook could not complete the operation one or more parameters are invalid still exists. Then there might be a problem with the PST file of Outlook. In such scenarios, you have to repair PST to fix this the parameters cname contains one or more parameters that are not valid.

Bringing It All Together

To summarize, Outlook error one or more parameters are not valid is one of the errors that occur while sending an email, assigning a task, or saving a new contact. In order to resolve the error, we have explained some manual tip & tricks. However, if the issue still persists due to harshly broken PST files then users can opt for the automated tool.