- “This is not a valid file name” is the phrase that accompanies a common problem in Outlook
- Microsoft’s email client offers some solutions, but they don’t always work
- What are the procedures that we suggest in case those do not work?
The experience for users who regularly use Outlook is generally stable and doesn’t cause too many problems. However, it is true that like any platform, this email client can experience bugs. By case, If you have come across that annoying error message, it will help you to know how to fix “This is not a valid file name” in Outlook forever.the warning that the name needs to be changed.

According to what those who use Outlook regularly say, this problem appears when trying to send an email. It does not matter if they are using it to send a new mail, as if they are trying to answer someone else’s mail. That message is simply shown to them and, no matter how many modifications they apply to the name, they do not advance further.
In English, the entire message basically discusses the problem and some possible solutions.:
This is not a valid file name.
Try one or more of the following:
*Check the path to make sure it was typed correctly.
*Select a file from the list of files and folders.
Clarified this then, the next thing will be to try to discover how to cancel said anomaly.
Fix “This is not a valid file name” step by step
Remove invalid special characters from file name
Of all the possible inconveniences, this would be the least serious.since we should only get rid of invalid special characters in Outlook file names, which are not supported by Microsoft.
Forward slash (/), backslash (), vertical bar (|) and colon (:) are some of the characters not supported by Outlook that Microsoft has released, so if you have any in the name, remove it.
Secondly, we recommend you also check the drive name in the file pathbecause if it has special characters, it is likely that you will encounter that same obstacle that we have been mentioning.
Finally, if there are no attachments, you have to continue with all the other solutions that we will mention.
Something similar could be that the body of the email contains image links that are hidden or broken. Convert text to HTML in plain text in the Text Formatting tab, and repair broken links.

Run Microsoft Support and Recovery Assistant
Microsoft Support and Recovery Assistant has been specially developed for these situations, and can help fix problems users frequently encounter when using Outlook on their PC.
- Enter to this linkwhere problems and solutions related to Outlook are raised
- Go to the end of the list and press Download, run it and go to the Other problems section
- Sign in to your Office 365 account and launch the Troubleshooting Wizard
Eventually, if the error persists, you can choose to launch an Advanced Diagnosticmuch deeper.

Run Outlook in safe mode and disable add-ins
If the previous solutions don’t work, try using Outlook in safe mode, disabling plugins. An outdated version of add-on software can sometimes conflict with Outlook.
- Manually start Outlook in safe mode and, if prompted, select your default profile
- Go to File, Options Plugins, and click on COM Plugins in the Manage menu
- In the list of plugins, clear all the checkboxes and click OK
It doesn’t make sense for you to press Delete, because deleting COM add-ins will only limit your Outlook. Once the add-ins are disabled, open Outlook as usual and see what happens then.
If the problem is resolved repeat the steps, but now to re-enable the plugins.

Repair Outlook Data Files
Nor could we rule out 100% that there is Outlook data file problems, PST and OST. These PST and OST formats are key within the mail client, since they save important data.
Inbox repair or SCANPST.EXE, has been developed to be able to fix them.
Other frequently asked questions
How do I fix an invalid file name?
To fix invalid filename error, you need to remove special characters from the name. Once this is done, if the error remains, look for spaces and remove them since they are not valid in the internal paths of Outlook.
What does invalid file name mean?
In short, a file name is said to be invalid if it contains special characters that Outlook does not support. Keep the file name to a reasonable length (less than 255 characters including the name of the route) and avoid special characters like colons (:), forward slash (/,), etc., ensures it is valid in Outlook.