"Upgrade Failed" on TBox Ultra: Corrupt File, FAT32, Free Space

Why it happens

Before a local update installs anything, the TBox Ultra unpacks the package and checks its signature. That is the long pause at 0%. If one byte of the file differs from what Carlinkit signed, the check fails and you get “Upgrade failed”, or on recent builds a message that the update file could not be verified and may be damaged.

A damaged file is the most common reason. Downloads through messaging apps and unstable mobile connections break more often than you would expect, and a copy to a cheap or failing card can corrupt the file again. The file still opens in an archiver, which is why owners rarely suspect it.

The other causes sit around the file rather than in it: a card the updater cannot read (one Ultra 4 owner’s update installed only from a FAT32 card), too little free storage for unpacking, or a system that was modified over ADB. If you enabled multitouch by hand or rooted the box, read update fails after disabling verity first, because no amount of re-downloading fixes that case.

Fixes, ranked

certutil -hashfile "C:\Downloads\update-file.zip" SHA256
certutil -hashfile "E:\update-file.zip" SHA256

Things to try (unverified)

• Install through update.zip instead of Local update. When verification fails, recent Ultra builds suggest renaming the package to update.zip, copying it to the root of the card (or of internal storage) and reinserting the card; the box then offers the update by itself. Delete or rename the file afterwards, or the prompt comes back at every start. Owners suggested this in several upgrade-failed threads, but none of those askers reported the result.
• Wait longer at 0%. On a TBox Plus, an owner explained that the box unpacks the file before the percentage moves and can stay at 0% for about five minutes. The asker planned to wait longer and did not report back.
• Set the stock launcher as default first. Carlinkit’s sellers link failed and bricked updates to third-party launchers, and it costs two minutes. See set the stock launcher before any firmware update.
• Check you did not change system files. Multitouch set up by hand, a remounted system partition or root all make the updater refuse the box. The undo is adb enable-verity, explained on the verity page.

If nothing works

Write down the model and firmware date from Settings → About, the exact name and size of the update file, how you downloaded it, the card’s size and format, the free storage, and the exact error text. A photo of the error screen helps.

Email Carlinkit support at [email protected] with that information and ask for the correct file for your unit; the full method is in the local FOTA update guide. If the box still works, staying on your current firmware is a reasonable answer: Carlinkit’s own upgrade guide advises against updating a box that is working well.

If a failed attempt left the box unable to boot, recovery is a QFIL flash of official images, described in recover a TBox Ultra with QFIL. If even that fails, a warranty claim or a replacement is the honest answer; start here compares the box families.