What the 1020 alarm means

One or more confirmation-required messages are still active, and KSS blocks the requested action until they are acknowledged. Our engineers run into this alarm every week on KUKA KRC2 / KRC4 / KRC5 (KSS) controllers, and a single on-site inspection usually identifies the problem.

Most common causes

  • An earlier fault was never cleared with the acknowledgment key
  • Message stack overflow hiding the original fault
  • An intermittent fault re-triggering the same message
  • Faulty acknowledgment key on the SmartPad
Field note: In our repair stats the first cause has the highest hit rate, so confirm it first before digging further.

Step-by-step field fix

  1. Open the message window and read the OLDEST active message — that is the root fault
  2. Clear the root cause first, then acknowledge
  3. If the stack is full, acknowledge and clear messages one by one from the log
  4. Check Diagnosis → Message Log for the recurring fault pattern
Safety first: For KUKA 1020, the risk on this family is not injury but data: lose the program, parameters and calibration data and weeks of teaching work start over. What you can check yourself first is Open the message window and read the OLDEST active message — that is the root fault; program and calibration data handling is not a DIY job.

How we diagnose system alarms on site

KUKA 1020 belongs to the system & program family. On KUKA 1020 the failing stage is KSS (KUKA System Software) (KRC2 / KRC4 / KRC5) on the KRC2 / KRC4 / KRC5 - the software layer: corrupted program or parameter files, boot failures, version mismatch, memory and storage media. We start reading KUKA 1020 at the smartPAD message window (KSS message numbers: 1xxx operator, 2xxxx drive) with KPP/KSP module LEDs.

The chain involved in KUKA 1020 runs: storage media (CF / flash / disk) -> system software and firmware -> parameters and calibration data -> user programs -> runtime.

KUKA 1020 is a system-family alarm, and our iron rule is: On system alarms we have an iron rule: however urgent the customer is, we take a complete backup first - programs, parameters, calibration data, tool and work-object frames, all of it. The reason is arithmetic: losing the live state here usually means weeks of teaching done again, which costs far more than a few hours of downtime. Only after the backup do we decide restart, restore or reinstall. If the storage media is already throwing errors we pull the data read-only first.

Field notes on this page cover KUKA 1020 (Pending Message Not Acknowledged ($CONF_MESS)); written by the Henghuan repair team, updated 2026-10-01.

Not sure? Don't force it — contact an engineer

Give us the alarm code, robot model and the action at the moment of the alarm, and our engineers can give you a quick read — phone or video remote diagnosis is free.

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Related System & Program alarms

1004 — File System Error 1015 — No Program Selected 1030 — External Start Missing ($EXT_START) 15102 — SmartPad (Teach Pendant) Fault
Same family: this code belongs to the System & program alarms family - the page collects all System & program-family codes we have handled, with the common inspection order and spares.
Other brands: we also keep field-fix libraries for ABB · Yaskawa · Universal Robots and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the KUKA 1020 alarm mean?

One or more confirmation-required messages are still active, and KSS blocks the requested action until they are acknowledged. Our engineers run into this alarm every week on KUKA KRC2 / KRC4 / KRC5 (KSS) controllers, and a single on-site inspection usually identifies the problem. KUKA 1020 sits in the system & program family; on our work orders the highest-frequency trigger for this code is "An earlier fault was never cleared with the acknowledgment key".

QCan I clear a KUKA 1020 alarm myself?

Whether KUKA 1020 clears on its own depends on the outcome of "Open the message window and read the OLDEST active message — that is the root fault". Finish the flow with "Check Diagnosis → Message Log for the recurring fault pattern" to confirm KUKA 1020 - do not skip it. If that step is clean, the second most frequent cause on KUKA 1020 is "Message stack overflow hiding the original fault". After clearing KUKA 1020, watch it for one shift. A second trip means stop and let an engineer arrive with the right test gear for program and calibration data.

QWhen you handle KUKA 1020, will my programs and frames get lost?

The commonest causes we see on KUKA 1020 are "An earlier fault was never cleared with the acknowledgment key, Message stack overflow hiding the original fault, An intermittent fault re-triggering the same message", so we stock the van against those. For KUKA 1020 specifically, we carry recovery media and common storage media, but on this family the backup matters more than the spare. For KUKA 1020, on system alarms the first move is backup; we can walk the customer through preserving data remotely before anything else. Before we roll, tell us what KUKA 1020 shows on the smartPAD message window (KSS message numbers: 1xxx operator, 2xxxx drive) with KPP/KSP module LEDs and what the machine was doing - phone or video triage is free.

The content on KUKA 1020 was written by Henghuan Robotics service engineers from hands-on repair experience. Alarm descriptions are our own reference summary and may differ by controller or software version — defer to KUKA documentation, or contact us to confirm. Henghuan is an independent service provider with no affiliation or endorsement by KUKA.