Why you're seeing this error
X caps how many posts an unverified account can publish per day. Two details matter more than the number itself:
The 50 is not one bucket you empty at your own pace. X splits it into half hour intervals, so a burst of 12 posts in ten minutes can block you well before you reach 50.
Everything counts. Posts from the X app, your browser, StreamLadder and any other scheduling tool all draw on the same 50.
What you can do
Wait 30 to 60 minutes, then hit Retry. If a burst tripped the half hour interval, that clears quickly. Failed posts are not sent again automatically, so open the post in the Content Publisher and click Retry.
Subscribe to X Premium. This lifts the cap, and it is the only real fix if you post heavily to X.
Post it manually. Note this draws on the same account limit, so it only helps if you are inside a half hour block rather than out of daily posts.
Go to your Exports tab.
Find the clip you want to post.
Click Download and save it to your device.
Upload it at x.com.
How to avoid it
Space your clips out, even on Premium. X's spam detection reacts badly to rapid posting.
Vary your captions. X rejects posts whose text closely matches something you posted in the last day or two, and the rejection often looks like a generic failure rather than a duplicate warning.
Source: X, understanding X limits. Last checked September 2026. X's own page still refers to an older 2,400 figure further down; 50 is the number being enforced.