I performed a firmware update on a configured SCALANCE M874-3 in the field. (The firmware was updated from V04.03.01 to V07.02.01).

After the update, the modem rebooted successfully, reestablished connections successfully, and traffic over the VPN resumed normally. However, the credentials, which worked for the admin login to the modem's WEB Management before the update now no longer work, instead yielding "Invalid username/password". (Since the credentials are kept in a password manager, a typo is not the cause.)

I should also mention that the password consists of 12 characters containing at least one of each of uppercase characters, lowercase characters, numerals, and special characters.

Is there any explanation for this, and is a recovery possible, or am I faced with a truck roll, factory reset, and complete reconfiguration? (This modem is at a remote site, accessed by VPN.)

Many thanks for taking the time to reply, Stefan.

I checked and can confirm that the modem did not return to the default login (admin:admin). I also looked up the default "High" password policy and can confirm that the current password meets it:

Password length: at least 8 characters, maximum 128 characters
At least 1 uppercase letter
At least 1 special character
At least 1 number

I have an opportunity to try this again on another identical modem tomorrow, where I will be physically at the modem's location. If I experience the same problem, I will be able to fully reset it and reapply the configuration. That might offer a clue as to what is going wrong.

Failing that, I will be sure to create a support request.

Either way, if I find the solution, I will note it here for others who may run into this issue.

Kind regards,

Anton

An update: I was able to duplicate this issue on a second modem (also a SCALANCE M874-3), which, when upgraded from firmware V04.03.01 to V07.02.01 suffered the same problem. In this case, I was in the field at the modem's location and was able to perform a factory reset. After the reset, the device started normally, in its factory default state, and running firmware V07.02.01. However, I had to reapply all the previous settings to return it to service.

After that, I had an opportunity to try a workaround on yet another remote modem (also a SCALANCE M874-3) with the same challenge; upgrading from firmware V04.03.01 to V07.02.01.

First, I tried upgrading from firmware V04.03.01 to V05.00, which was successful, and did not create the same problem with login credentials.

I then upgraded from firmware V05.00 to V06.02, which was also successful and did not create the same problem with login credentials.

Finally, I upgraded from firmware V06.02 to V07.02.01, which was successful and did not create the same problem with login credentials.

So it seems the guidance is to upgrade firmware by no more than one major version increment at a time.