diff --git a/classes/contextinfo.php b/classes/contextinfo.php
index 4f40b67..b15a989 100644
--- a/classes/contextinfo.php
+++ b/classes/contextinfo.php
@@ -110,7 +110,7 @@ class contextinfo {
      * @param int $contextid Context id
      * @return context The context
      */
-    private static function context_by_id($contextid): \context {
+    public static function context_by_id($contextid): \context {
         if ($contextid <= 1) {
             $contextid = 1;
         }
diff --git a/classes/studyplan.php b/classes/studyplan.php
index a12e8f9..dbc3405 100644
--- a/classes/studyplan.php
+++ b/classes/studyplan.php
@@ -192,13 +192,18 @@ class studyplan {
      * @return \context
      */
     public function context(): \context {
+        global $DB;
         if (!isset($this->context)) {
             try {
-                $this->context = contextinfo::by_id($this->r->context_id)->context;
+                $this->context = contextinfo::context_by_id($this->r->context_id);
             } catch (\dml_missing_record_exception $x) {
-                // Just throw it up again. catch is included here to make sure we know it throws this exception.
-                throw new \InvalidArgumentException(
-                    "Context {$this->r->context_id} not available");
+                /* The associated context cannot be found.
+                   Probably the category was removed, but the studyplan was not.
+                   Revert the studyplan back to the system context to avoid lost studyplans.
+                */
+                $this->context = \context_system::instance();
+                $this->r->context_id = $this->context->id;
+                $DB->update_record(self::TABLE, $this->r);
             }
         }
         return $this->context;
diff --git a/db/services.php b/db/services.php
index cf78b79..8d8748b 100644
--- a/db/services.php
+++ b/db/services.php
@@ -557,7 +557,7 @@ $functions = [
         'loginrequired' => true,
     ],
     'local_treestudyplan_bulk_course_timing' => [         // Web service function name.
-        'classname'     => '\local_treestudyplan\utilityservice',  // Class containing the external function.
+        'classname'     => '\local_treestudyplan\studyplanservice',  // Class containing the external function.
         'methodname'    => 'bulk_course_timing',          // External function name.
         'description'   => 'Change course start/end dates to match that of the studyplan period',
         'type'          => 'write',                  // Database rights of the web service function (read, write).
diff --git a/version.php b/version.php
index db0ffd6..9a0ceb1 100644
--- a/version.php
+++ b/version.php
@@ -22,7 +22,7 @@
 defined('MOODLE_INTERNAL') || die();
 
 $plugin->component = 'local_treestudyplan';  // Recommended since 2.0.2 (MDL-26035). Required since 3.0 (MDL-48494).
-$plugin->version = 2023121302;  // YYYYMMDDHH (year, month, day, iteration).
+$plugin->version = 2023121304;  // YYYYMMDDHH (year, month, day, iteration).
 $plugin->requires = 2021051700; // YYYYMMDDHH (This is the release version for Moodle 3.11).
 
 $plugin->release = "1.1.0";