Serge_1980,

To start would you confirm if you have a complete backup, if anything changed prior to this happening, and if the data is still accessible. 

Now to the error you're seeing on your SC5020s controllers:

HTTPMainRequest::TimerCallback - Oldtimeout

is typically associated with controller communication delays or failures in the internal HTTP service used by the Storage Center OS for inter-process messaging and management interface operations. The error suggests that a timeout occurred while the controller was waiting for a response from an internal service or peer controller.

This can happen due to 

One controller is unresponsive or failed.
There is a lead controller election issue.
The system is stuck in a boot or failover loop.
There is a firmware mismatch or corruption.

What I would suggest is the following;

1. Check Controller Status
Connect via serial console or SSH.
Use the CLI command:
Chassis show
This may show controller status even in safe mode.

2. Attempt to Bypass Controller Election
If one controller is down, you can force the other to become leader:

fm leader ignore <HSN of failed controller>

You’ll be prompted to confirm.
This allows the healthy controller to boot and assume leadership.

3. Reset HTTP Service (if applicable)
If the web interface is inaccessible but CLI works, you can try restarting the HTTP service:
service restart http
Now this command may not be available in safe mode or without elevated support access.

4. Firmware Validation

Ensure both controllers are running matching firmware versions.
If one controller was recently updated or replaced, mismatch can cause boot and communication errors.

Now on a side note, do not attempt to reinitialize or reset both controllers, as that can result in data loss. 
Also, always document the current state and collect logs before making changes.

Let me know if this helps.

@DELL-Chris H ​ Thank you for answer! we check this

Also we have a automatic failover problem between two storages, but manual failover / failback working fine for the test live volume.

The auto failover problem might be unrelated, or even on this system, we can look into that as well.

This is chassis show output
  Firmware Versions 10/10/2025 12:10:35 PM

                            Name                                           Component ID                        Install Date             Version String
============================================================ ======================================== ============================== ====================
SCOS Firmware Package                                        SCOS:package:000000                                   N/A                     59D833FA
10/10/2025 12:10:35 PM,7:01:22:48.840_831_266] System Debug: Error collecting overall CPU usage data, RETVal: Unsupported_Option
Power Supply.Slot.1                                          DCIM:firmware:102584                          2021-10-25T08:36:43Z            00.05.20
Power Supply.Slot.2                                          DCIM:firmware:102584                          2021-10-25T08:36:43Z            00.05.20
10/10/2025 12:10:37 PM,7:01:22:50.843_764_636] System Debug: Error collecting overall CPU usage data, RETVal: Unsupported_Option
Integrated Remote Access Controller                          DCIM:firmware:25227                           2020-05-27T07:27:54Z           0.49.11.11
Battery Backup Unit.1                                        DCIM:firmware:104086                          2020-05-27T07:27:53Z           A9.C2.C26
Intel(R) I350 Gigabit Network Connection - 2C:EA:7F:45:10:CB DCIM:firmware:8086:1521:1028:1FAE             2020-05-27T07:38:59Z
Intel(R) I350 Gigabit Backplane Connection - 2C:EA:7F:45:10: DCIM:firmware:8086:1523:1028:1FAE             2020-05-27T07:39:03Z
BIOS                                                         DCIM:BIOS:159                                 2020-05-27T07:38:53Z             2.4.2
Lifecycle Controller                                         DCIM:firmware:28897                           2020-05-27T07:27:58Z           0.49.11.11
Diagnostics                                                  DCIM:firmware:25806                           2020-05-27T07:27:58Z               0
OS Drivers Pack                                              DCIM:firmware:18981                           2020-05-27T07:27:58Z               0
10/10/2025 12:10:39 PM,7:01:22:52.845_733_032] System Debug: Error collecting overall CPU usage data, RETVal: Unsupported_Option
OS Collector                                                 DCIM:firmware:101734                          2020-05-27T07:27:58Z               0
System CPLD                                                  DCIM:firmware:27763                           2020-05-27T07:27:58Z             0.9.14
Identity Module                                              DCIM:firmware:102200                          2020-05-27T07:27:59Z              1.01

@DELL-Chris H ​ 

Hello!

command service restart http does not work

what we do wrong?

Thank you

I apologize, so you would need to restart the I would ensure both controllers are running the same SCOS firmware version, as mismatched firmware or corruption can cause HTTP service failures.

I made a mistake in the previous message, as the only supported method is to restart the entire controller, which can be done via the CLI or by physically rebooting the controller.

For CLI i believe it is

system reboot controller

@DELL-Chris H ​ 

Thank you.

I posted the command chassis show output earlier, can you take a look?

Is command system reboot controller safe to run and will it not reset my settings?

Hi, as i know yes, the system reboot controller command is safe to run. It won’t wipe your configuration or data it just performs a reboot, similar to a power cycle. Make sure you target the correct controller and avoid rebooting both at the same time unless instructed.

@DELL-Erman O​ Hello!

Restarting the controllers didn't help. 

We turned off one controller, and the alarms continued—so it's not a matter of interaction between controllers...maybe the controller is trying to access some external resources? We turned off the support assist service just in case, but it didn't help.

Serge_1980,

There is a page here that covers the same issue, with a customer based solution listed, but as stated by another tech it does have its risks.

You may want to try dpayne-2014s solution, or consider calling into support so that we can review the logs and work directly with the system.

Let me know if this helps.