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    <para>

     

       
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144
       
 
       
     <literal>lib.strict</literal> is removed. Use

     

       
145
       
 
       
     <literal>builtins.seq</literal> instead.

     

       
146
       
 
       
    </para>

     

···

       
141
       
 
       
   </listitem>

     

       
142
       
 
       
   <listitem>

     

       
143
       
 
       
    <para>

     

       
144
       
+
       
     The minimum version of Nix required to evaluate Nixpkgs is now 2.0.

     

       
145
       
+
       
    </para>

     

       
146
       
+
       
    <itemizedlist>

     

       
147
       
+
       
     <listitem>

     

       
148
       
+
       
      <para>

     

       
149
       
+
       
       For users of NixOS 18.03, NixOS 18.03 defaulted to Nix 2.0, but

     

       
150
       
+
       
       supported using Nix 1.11 by setting <literal>nix.package =

     

       
151
       
+
       
       pkgs.nix1;</literal>. If this option is set to a Nix 1.11 package, you

     

       
152
       
+
       
       will need to either unset the option or upgrade it to Nix 2.0.

     

       
153
       
+
       
      </para>

     

       
154
       
+
       
     </listitem>

     

       
155
       
+
       
     <listitem>

     

       
156
       
+
       
      <para>

     

       
157
       
+
       
       For users of NixOS 17.09, you will first need to upgrade Nix by setting

     

       
158
       
+
       
       <literal>nix.package = pkgs.nixStable2;</literal> and run

     

       
159
       
+
       
       <command>nixos-rebuild switch</command> as the <literal>root</literal>

     

       
160
       
+
       
       user.

     

       
161
       
+
       
      </para>

     

       
162
       
+
       
     </listitem>

     

       
163
       
+
       
     <listitem>

     

       
164
       
+
       
      <para>

     

       
165
       
+
       
       For users of a daemon-less Nix installation on Linux or macOS, you can

     

       
166
       
+
       
       upgrade Nix by running <command>curl https://nixos.org/nix/install |

     

       
167
       
+
       
       sh</command>, or prior to doing a channel update, running

     

       
168
       
+
       
       <command>nix-env -iA nix</command>.

     

       
169
       
+
       
      </para>

     

       
170
       
+
       
      <para>

     

       
171
       
+
       
       If you have already run a channel update and Nix is no longer able to

     

       
172
       
+
       
       evaluate Nixpkgs, the error message printed should provide adequate

     

       
173
       
+
       
       directions for upgrading Nix.

     

       
174
       
+
       
      </para>

     

       
175
       
+
       
     </listitem>

     

       
176
       
+
       
     <listitem>

     

       
177
       
+
       
      <para>

     

       
178
       
+
       
       For users of the Nix daemon on macOS, you can upgrade Nix by running

     

       
179
       
+
       
       <command>sudo -i sh -c 'nix-channel --update &amp;&amp; nix-env -iA

     

       
180
       
+
       
       nixpkgs.nix'; sudo launchctl stop org.nixos.nix-daemon; sudo launchctl

     

       
181
       
+
       
       start org.nixos.nix-daemon</command>.

     

       
182
       
+
       
      </para>

     

       
183
       
+
       
     </listitem>

     

       
184
       
+
       
    </itemizedlist>

     

       
185
       
+
       
   </listitem>

     

       
186
       
+
       
   <listitem>

     

       
187
       
+
       
    <para>

     

       
188
       
 
       
     <literal>lib.strict</literal> is removed. Use

     

       
189
       
 
       
     <literal>builtins.seq</literal> instead.

     

       
190
       
 
       
    </para>