GS108Ev2 incorrect password after restoring configuration

Minimal summary

Only upgrade firmware if you know you need to. Recovering old config files is a major hassle, if it's possible at all.

Discussion

I think I found out what happened.

(From GS108Ev2 firmware v1.00.12 release notes)

WARNING - Please make sure the version of the Prosafe Plus Utility installed on your PC is v2.2.24 or newer before upgrading the GS108Ev2 firmware. Older versions of the Plus Utility do not support the password encryption required by V1.00.10 firmware.

In my understanding, what this means is:

To restore old configurations, the switches must be downgraded to firmware v1.00.09 or older. Otherwise the unencrypted passwords of old firmware versions won't be correctly read by newer firmware versions from 1.00.10 onwards, so you will be locked out of the switch until you reset it to factory.

The Prosafe utility must be downgraded to v2.2.23 or older too, or it will try to encrypt the passwords and the older firmare versions won't be able to read them, since they expect them uncrypted.

I reiterate my suggestion to the developers: at least put a cleartext header in the config file, so the switch (or the user!) knows which firmware version saved it. If you want to make it really functional, have appropriate checks at load (restore) time, so old unencrypted passwords keep on working on new firmware versions.