Removing a file extension during the renaming process on an operating system like Windows or macOS can lead to an incomplete or unusable file name. File extensions (e.g., .txt, .jpg, .docx) are crucial identifiers that tell your computer which application should open the file. When you start renaming a file and delete the extension, then complete the rename action, the operating system interprets the new name as lacking an extension entirely. The original file type association is broken.

For example, if you're renaming report.docx to final report and remove .docx, Windows or macOS will register the filename simply as final report with no extension. Consequently, your system may display a generic icon and won't know to open it with Microsoft Word. Similarly, renaming photo.jpg to vacation_pic without the .jpg extension prevents image viewers from recognizing it as a picture file, making it difficult to open correctly.

The major limitation is that the file becomes disassociated from its intended program, requiring manual intervention to restore the correct extension. You might need to right-click the file, rename it again to add the proper suffix (like .docx), or choose "Open With" to specify an application. While this typically doesn't corrupt the actual data inside the file, it causes inconvenience and potential confusion. To prevent this, always ensure the file extension remains visible and unchanged during renaming unless intentional modification is required.