diff --git a/about.pl b/about.pl
index 066db24e44..2135399a14 100755
--- a/about.pl
+++ b/about.pl
@@ -518,6 +518,13 @@ $template->param( 'bad_yaml_prefs' => \@bad_yaml_prefs ) if @bad_yaml_prefs;
     }
 }
 
+{
+    # Test 'key' config for Pseudonymization
+    $template->param( config_key_no_set => 1 )
+      if C4::Context->preference('Pseudonymization')
+      and not C4::Context->config('key');
+}
+
 my %versions = C4::Context::get_versions();
 
 $template->param(
diff --git a/koha-tmpl/intranet-tmpl/prog/en/modules/about.tt b/koha-tmpl/intranet-tmpl/prog/en/modules/about.tt
index 7448d4094c..d3dae647cf 100644
--- a/koha-tmpl/intranet-tmpl/prog/en/modules/about.tt
+++ b/koha-tmpl/intranet-tmpl/prog/en/modules/about.tt
@@ -184,7 +184,7 @@
         </div>
 
         <div id="sysinfo">
-    [% IF warnPrefBiblioAddsAuthorities || warnPrefEasyAnalyticalRecords || warnPrefAnonymousPatronOPACPrivacy || warnPrefAnonymousPatronAnonSuggestions || warnPrefAnonymousPatronOPACPrivacy_PatronDoesNotExist || warnPrefAnonymousPatronAnonSuggestions_PatronDoesNotExist || warnNoActiveCurrency || warnIsRootUser || xml_config_warnings.size || AutoSelfCheckPatronDoesNotHaveSelfCheckPerm || AutoSelfCheckPatronHasTooManyPerm || warnStatisticsFieldsError || warnNoTemplateCaching || warnILLConfiguration || has_ai_issues || oauth2_missing_deps || bad_yaml_prefs || warnRelationships || log4perl_errors %]
+    [% IF warnPrefBiblioAddsAuthorities || warnPrefEasyAnalyticalRecords || warnPrefAnonymousPatronOPACPrivacy || warnPrefAnonymousPatronAnonSuggestions || warnPrefAnonymousPatronOPACPrivacy_PatronDoesNotExist || warnPrefAnonymousPatronAnonSuggestions_PatronDoesNotExist || warnNoActiveCurrency || warnIsRootUser || xml_config_warnings.size || AutoSelfCheckPatronDoesNotHaveSelfCheckPerm || AutoSelfCheckPatronHasTooManyPerm || warnStatisticsFieldsError || warnNoTemplateCaching || warnILLConfiguration || has_ai_issues || oauth2_missing_deps || bad_yaml_prefs || warnRelationships || log4perl_errors || config_key_no_set %]
         [% IF (warnIsRootUser) %]
             <h2>Warning regarding current user</h2>
             <p>You are logged in as the database administrative user. This is not recommended because some parts of Koha will not function as expected when using this account.</p>
@@ -259,7 +259,7 @@
             [% END %]
         [% END %]
 
-        [% IF warnPrefBiblioAddsAuthorities || warnPrefEasyAnalyticalRecords || warnPrefAnonymousPatronOPACPrivacy || warnPrefAnonymousPatronAnonSuggestions || warnPrefAnonymousPatronOPACPrivacy_PatronDoesNotExist || warnPrefAnonymousPatronAnonSuggestions_PatronDoesNotExist || warnNoActiveCurrency || AutoSelfCheckPatronDoesNotHaveSelfCheckPerm || AutoSelfCheckPatronHasTooManyPerm || warnStatisticsFieldsError || warnNoTemplateCaching || warnILLConfiguration || oauth2_missing_deps || bad_yaml_prefs || warnIssuingRules %]
+        [% IF warnPrefBiblioAddsAuthorities || warnPrefEasyAnalyticalRecords || warnPrefAnonymousPatronOPACPrivacy || warnPrefAnonymousPatronAnonSuggestions || warnPrefAnonymousPatronOPACPrivacy_PatronDoesNotExist || warnPrefAnonymousPatronAnonSuggestions_PatronDoesNotExist || warnNoActiveCurrency || AutoSelfCheckPatronDoesNotHaveSelfCheckPerm || AutoSelfCheckPatronHasTooManyPerm || warnStatisticsFieldsError || warnNoTemplateCaching || warnILLConfiguration || oauth2_missing_deps || bad_yaml_prefs || warnIssuingRules || config_key_no_set %]
             <h2>Warnings regarding the system configuration</h2>
             <table>
                 <caption>Preferences and parameters</caption>
@@ -335,6 +335,11 @@
                     Some system preferences have badly formatted YAML content: [% bad_yaml_prefs.join(', ') | html %]
                     </td></tr>
                 [% END %]
+                [% IF config_key_no_set %]
+                    <tr><th scope="row"><b>Warning</b> </th><td>
+                    System preference 'Pseudonymization' is set, but there is not 'key' entry defined in the $KOHA_CONF file.
+                    </td></tr>
+                [% END %]
             </table>
         [% END %]