Desktop Environment (if applicable):
XFCE,
Linux laptop 6.17.0-20-generic #20~24.04.1-Ubuntu SMP PREEMPT_DYNAMIC Thu Mar 19 01:28:37 UTC 2 x86_64 x86_64 x86_64 GNU/Linux
Problem Description:
journalctl writes since April 8th 2026:
Apr 08 12:27:41 laptop kernel: usb 3-6.4-port2: disabled by hub (EMI?), re-enabling…
Apr 10 15:01:19 laptop kernel: usb 3-6.4-port2: disabled by hub (EMI?), re-enabling…
Apr 10 15:01:29 laptop kernel: usb 3-6.4-port2: disabled by hub (EMI?), re-enabling…
Apr 19 15:31:11 laptop kernel: usb 3-6.4-port2: disabled by hub (EMI?), re-enabling…
Relevant System Information:
There are only few postings on the internet about this issue, some assuming, that this is an issue of newer kernels. Are the Ubuntu guys aware of this bug?
disabled by hub (EMI?), re-enabling… is a generic USB subsystem warning that has existed for many years across Linux distributions. It indicates that the USB hub/controller temporarily disabled a port due to a detected error condition, then attempted to enable it again automatically.
Despite the “EMI?” wording, it does not strictly mean electromagnetic interference. It’s a fallback message used when the hub detects a port error or protocol issue. According to USB behavior, ports can be disabled due to internal errors, signal issues, or unstable communication, not just EMI.
Common real-world causes reported across systems include:
Faulty or low-quality USB cables
Unstable or underpowered USB devices
Power delivery issues (especially on laptops or unpowered hubs)
Hardware/controller quirks (motherboard or USB chipset)
In some cases, kernel/driver regressions, but less common
In many cases, you’ll also see follow-up logs like disconnect/reconnect or enumeration failures, confirming it’s a physical or