I add to my sources.list file this repository:

deb http://mirrordirector.raspbian.org/raspbian/ stretch main contrib non-free rpi

I need that to install php7.0 on my raspberry pi, after I execute command in terminal:

_ apt-get install -t stretch mysql-server mysql-client php7.0-mysql -y

now always when I try to install any package I got many messages like this:

Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/^(.*?)(\\)?\${ <-- HERE ([^{}]+)}(.*)$/ at /usr/share/perl5/Debconf/Question.pm line 72.
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/\${ <-- HERE ([^}]+)}/ at /usr/share/perl5/Debconf/Config.pm line 30.

of course I install them properly but message looks weird.

Anyone could tell me what it means and how to solve it?


it's reported upstream and upstream reports it being fixed in 2015:


however i still see that error on my debian 8.8 with debconf-1.5.56.all installed, the machine was installed in 2016.

to fix this, i ran apt-get install debconf

you may run apt-get dist-upgrade to update all packages in system, but beware it may update to 8.8 -> 9.0


It's a warning. The folks who maintain that code will need to escape the left braces, e.g. change { in the regular expression to \{. Reporting this to the folks to maintain that code may help, as it's a trivial fix.

  • Can you tell me which file should I edit? Or if I'm wrong, they should edit file on repo? – kuchar Dec 24 '16 at 16:23
  • Any updates on reporting this? – David Refoua Mar 11 '17 at 20:18
  • The error warning tells you in which file and line you have to search – rubo77 Feb 8 '18 at 19:49

you simply have to open the file that is mentioned within the warning

m/^(.?)(\)?\${ <-- HERE ([^{}]+)}(.)$/ at /usr/share/perl5/Debconf/Question.pm line 72.

go to the mentioned line 72 and add a backslash in front of the left brace where the warning points to with <-- HERE

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