ISPConfig Migration Toolkit Debian 12 Dash is incompatible

We plan to make it compatible, but this will take some time. You can use it with an alternate PHP version in the way you described it, that's why this option was added to the Tool. We are also working on making it available as Docker image to prevent such incompatibilities.

That's a known issue in Debian 12 that dpkg-reconfigure command refuses to disable dash. The Migration Tool uses complex bash scripts, and dash is simply not capable of running them. The solution is to temporarily rename /bin/sh (which is a symlink) and then create a new symlink for /bin/sh that points to bash instead of dash.

 

There used to be a command to do this, dpkg-reconfigure, which does not obey the selection that the administrator (root user) of a system has chosen for the shell anymore. So, I would call this a bug as the command and config option for dash still exists, even if they might call it a feature. It's OK if Debian devs decide that they like this misbehavior of the command, which means they render their command useless, so we will have to start providing our own code to fix what they broke in Debian 12.

The reason why this is an issue is simply that all PHP binaries have hardcoded references to /bin/sh, so even if you run a php script with bash on the shell, it will execute commands internally that are run with exec with dash if /bin/sh is linked to dash, so there is no workaround as either changing /bin/sh to a more capable shell than dash or changing PHP sources and recompile PHP.