Google's Connect your Chromebook to Thunderbolt and USB4 accessories article is the main source for a USB-C device that will not work: make sure both the Chromebook and the accessory support USB4 and Thunderbolt (compatible devices often show a Thunderbolt image on the connector); to connect new Thunderbolt or USB4 accessories you must be signed in and the screen must be unlocked; and if a Thunderbolt accessory does not work automatically,
you may need to turn off the setting under Settings, Privacy and security, Block Thunderbolt or USB4 accessories from accessing and sharing memory. If you cannot find that setting, your Chromebook does not support USB4 or Thunderbolt. For an ordinary USB-A or USB-C drive, mouse or hub, the steps are the same as anywhere: try another cable and port, remove hubs, restart. Guest mode limits accessories, and a school or work Chromebook may block them.
Differential
Likely causes of “Acer Chromebook Plus 514 USB or Thunderbolt device is not recognized”, and how to tell them apart
- 1
The accessory or Chromebook does not support USB4 or Thunderbolt
What separates it A Thunderbolt dock does nothing because the accessory or the Chromebook does not support USB4
How to confirm Check both support it; look for the Thunderbolt image on the connector, as Google says
- 2
You are not signed in or the screen is locked
What separates it A new accessory is ignored because you are not signed in or the screen is locked
How to confirm Sign in and unlock the screen, as Google's article requires
- 3
Memory-access protection blocks the accessory
What separates it A Thunderbolt accessory is detected and does not work
How to confirm Turn off the block setting under Settings, Privacy and security, for a trusted accessory
- 4
A bad cable or hub
What separates it The device fails on one cable and works on another
How to confirm Swap the cable and remove the hub, and test the accessory again
- 5
Guest mode or an administrator policy
What separates it Accessories have limited performance or are blocked because of guest mode or an administrator policy
How to confirm Sign in to your account; on a managed Chromebook, ask your administrator
Before you touch a setting
Record this first — changing settings destroys the evidence
- Which accessory fails, its make and connector, and whether it works on another computer
- Whether you are signed in, in guest mode, or using a managed Chromebook
- Whether the Block Thunderbolt or USB4 accessories setting exists in Settings, Privacy and security
Try in this order
0 of 7 completedTry another cable and port
ReversibleTry another cable and port, by swapping the cable and using the other USB-C port if the model has one.
Sign in and unlock
ReversibleSign in and unlock, since Google says that new Thunderbolt or USB4 accessories need a signed in, unlocked Chromebook.
Check support
ReversibleCheck support, by looking for the Thunderbolt image on the connector and the Privacy and security setting.
Toggle the protection setting
ReversibleToggle the protection setting, and for a trusted accessory, turn the block setting off and on again.
Reconnect
ReversibleReconnect, by waiting a few seconds, disconnecting and reconnecting the accessory, as Google suggests, and then test again to see whether it helped.
Remove hubs and other devices
ReversibleRemove hubs and other devices, and test the accessory alone on the port, and then test again to see whether it helped.
Hard reset if it persists
ReversibleHard reset if it persists, by backing up Downloads first, then following Google's hardware reset.
Model-specific
What is true of this model and not of its siblings
- Which ports support what
- Google says Chromebooks with select processors support USB4 and Thunderbolt. Whether yours does is on the label or Acer's product page for your model number.
- Repair cost
- A port that ignores one cable is usually the cable or a setting. A port repair at an independent shop is about $129 to $179 per BadgerLayer, with a free diagnostic.
Stop boundary
When this stops being a self-service repair
- !If a known-good accessory and cable fail in every port, contact Acer Support
- !If the port is loose or damaged, book a repair and stop using it
- !If an accessory is unsupported, send feedback to Google as its article describes
Evidence ledger
Sources behind this answer
Signed-in requirement, the memory-access protection setting, supported accessories and guest mode.
The index of Chromebook hardware and connection fixes.
The hard reset for stubborn hardware faults.
The Chromebook and ChromeOS platform.
Shop price ranges for screen, battery, keyboard and charging-port repairs.
Exact questions
Common questions
What if a drive is not formatted for ChromeOS?+
A Chromebook reads common formats but not every one. Check the drive's format, and back up before reformatting anything.
Do phones connect over USB?+
A phone can charge from a Chromebook port, and Google's article on file types and external devices lists what works. Check the cable carries data, not only power.
Should I use a powered hub?+
For drives and webcams, yes. A busy unpowered hub can starve a device, so test the device alone first.
Does every USB-C port support Thunderbolt?+
No. Google says both the Chromebook and the accessory must support USB4 and Thunderbolt, and if the setting is missing in Privacy and security, the Chromebook does not.
Why must I be signed in?+
Google's article says new Thunderbolt or USB4 accessories connect only when you are signed in and the screen is unlocked.
What does the memory protection setting do?+
It blocks Thunderbolt or USB4 accessories from accessing and sharing memory. Google turns it on by default for security and says a Thunderbolt accessory may need it off.
Why is my dock slow in guest mode?+
Google says you cannot turn off the protection in guest mode, so accessories may still work with limited performance.
Which accessories work?+
Google lists docks, displays and storage accessories among the supported types.
Can a school Chromebook block USB drives?+
Yes. A managed Chromebook may block storage by policy. Ask your administrator.