Could be a YouTube problem? Assume you were attempting a direct upload from VP. Occasionally, due to server load, those fail.
Export your video as an mp4 (or any other YouTube approved format) and use their uploader. Let us know how it went.
https://support.google.com/youtube/answer/57407?co=GENIE.Platform%3DDesktop&hl=en
If you like, we can test a YouTube direct upload for you. Just share the project and someone will check it out. Here's how...
1. With your project on the timeline, click on MENU at the top-left. Click FILE|BACK UP PROJECT FILES TO FOLDER. Choose a folder and SELECT FOLDER.
2. Locate the saved, numbered folder and upload it to a free server - Google Drive, MS OneDrive, etc.* (Don't upload the export or just the VPJ file.)
3. Get a shared, public link. If using Google Drive click GET SHAREABLE LINK. Click the blue "Change to anyone with the link..." Then click COPY LINK | DONE.
4. Paste that link here, or click the folder, above top-right in this forum, and message it to me. This is private and won't be shared.
* Before uploading, right-click the folder, click PROPERTIES. Look at the File Size to confirm that it's not too big for the free space on the server.