diff --git a/application/views/scripts/error/error.phtml b/application/views/scripts/error/error.phtml
index b66d5b4eda..9a62803b94 100644
--- a/application/views/scripts/error/error.phtml
+++ b/application/views/scripts/error/error.phtml
@@ -23,7 +23,7 @@ $modReason = [];
 
 if (isset($requiredVendor, $requiredProject) && $requiredVendor && $requiredProject) {
     // TODO: I don't like this, can we define requirements somewhere else?
-    $coreDeps = ['icinga-php-library' => '>= 0.14.2', 'icinga-php-thirdparty' => '>= 0.12'];
+    $coreDeps = ['icinga-php-library' => '>= 0.18.0', 'icinga-php-thirdparty' => '>= 0.12'];
 
     foreach ($coreDeps as $libraryName => $requiredVersion) {
         if (! $libraries->has($libraryName)) {
diff --git a/doc/02-Installation.md b/doc/02-Installation.md
index ddca8bcf4c..8e7fb88520 100644
--- a/doc/02-Installation.md
+++ b/doc/02-Installation.md
@@ -399,7 +399,7 @@ You will need to install certain dependencies depending on your setup:
   monitor your infrastructure
 * A web server, e.g. Apache or Nginx
 * PHP version ≥ 7.2
-* [Icinga PHP Library (ipl)](https://github.com/Icinga/icinga-php-library) (≥ 0.14.2)
+* [Icinga PHP Library (ipl)](https://github.com/Icinga/icinga-php-library) (≥ 0.18.0)
 * [Icinga PHP Thirdparty](https://github.com/Icinga/icinga-php-thirdparty) (≥ 0.12)
 * The following PHP modules must be installed: cURL, json, gettext, fileinfo, intl, dom, OpenSSL and xml
 * The [pdfexport](https://github.com/Icinga/icingaweb2-module-pdfexport) module (≥0.10) is required for the
diff --git a/modules/setup/library/Setup/WebWizard.php b/modules/setup/library/Setup/WebWizard.php
index cfc961d6dc..ca9ce2bb0d 100644
--- a/modules/setup/library/Setup/WebWizard.php
+++ b/modules/setup/library/Setup/WebWizard.php
@@ -602,7 +602,7 @@ public function getRequirements($skipModules = false)
         )));
 
         $set->add(new WebLibraryRequirement(array(
-            'condition'     => ['icinga-php-library', '>=', '0.14.2'],
+            'condition'     => ['icinga-php-library', '>=', '0.18.0'],
             'alias'         => 'Icinga PHP library',
             'description'   => mt(
                 'setup',
diff --git a/public/css/icinga/main.less b/public/css/icinga/main.less
index 11f9da8bea..d0090b776e 100644
--- a/public/css/icinga/main.less
+++ b/public/css/icinga/main.less
@@ -6,10 +6,6 @@
 // Width for the name column--th--of name-value-table
 @name-value-table-name-width: 38/3em;
 
-.action-link {
-  color: @icinga-blue;
-}
-
 .error-message {
   font-weight: @font-weight-bold;
 }
@@ -126,22 +122,6 @@ a:hover > .icon-cancel {
   .fg-stateful();
 }
 
-// Link styles
-
-.button-link {
-  .action-link();
-  .rounded-corners(3px);
-
-  background: @low-sat-blue;
-  display: inline-block;
-  padding: 0.25em 0.5em;
-
-  &:hover {
-    background: @low-sat-blue-dark;
-    text-decoration: none;
-  }
-}
-
 // List styles
 
 .comment-list {
diff --git a/public/css/icinga/mixins.less b/public/css/icinga/mixins.less
index 6c555127b1..5b28b1ede4 100644
--- a/public/css/icinga/mixins.less
+++ b/public/css/icinga/mixins.less
@@ -60,13 +60,6 @@
           transform: @transform;
 }
 
-.user-select(@user-select) {
-  -webkit-user-select: @user-select;
-  -moz-user-select: @user-select;
-  -ms-user-select: @user-select;
-  user-select: @user-select;
-}
-
 .transition (@transition) {
   -webkit-transition: @transition;
      -moz-transition: @transition;