Why Did My Upload Fail?
Most failed uploads hit a size limit - 5 MB per HTML page, 25 MB per other file, 100 MB per ZIP, or your account's storage pool is full. Other causes: no index.html at the top level, a file type that is not allowed, or an unverified email address. The error message on the upload page names the problem.
Updated
The upload page names the problem next to each file, so start by reading the message. These are the causes, most common first.
A File Is Over Its Size Limit
Each HTML page can be up to 5 MB, any other file up to 25 MB, and a ZIP up to 100 MB. An oversized file shows as skipped. Compress large images (WebP helps a lot) or split very large pages.
Very large publishes can also hit a per-publish transport limit - the message "Uploads over 4.0 MB aren't supported in one publish yet - trim the largest files." means the whole upload was too big to send in one go. Move big images into the Media Library, which takes files up to 10 MB each, and reference them from your pages instead of including them in the upload.
Your Storage Is Full
Storage is pooled across your account: 5 MB on Free, 500 MB on Starter, 2 GB on Growth, 10 GB on Pro, 20 GB on Agency. Delete unused files, websites or media, or upgrade.
No index.html At The Top Level
File, folder and ZIP uploads need an index.html at the top level - that
is the page visitors see at /. A common cause is a ZIP that contains a
folder which contains the site; zip the files themselves, not the folder
around them. With Upload Files you can instead pick a homepage and it is
published as index.html for you.
A File Type Is Not Allowed
Uploads accept the file types a static site uses: HTML, CSS, JS, JSON,
images (PNG, JPG, WebP, GIF, SVG, ICO), fonts (WOFF, WOFF2), PDF, plus
robots.txt and sitemap.xml. Other types show as "Skipped - type not
allowed". System junk like .DS_Store and Thumbs.db is skipped
automatically - that is normal and nothing is wrong.
ZIP Limits
A ZIP can hold up to 1000 files and up to 150 MB once unpacked.
Your Email Is Not Verified
Publishing requires a verified email address. Use the resend link in your dashboard, open the emailed link, and publish again.
A Content Message Appears
If publishing stops with "There seems to be an error with your content. Please contact support.", the upload was held by an automated content check. Contact support and we will take a look.