diff --git a/lib/pagelib.php b/lib/pagelib.php
index c650dadf148..d39b5f2a0db 100644
--- a/lib/pagelib.php
+++ b/lib/pagelib.php
@@ -965,7 +965,11 @@ class moodle_page {
             } else {
                 // We do not want devs to do weird switching of context levels on the fly because we might have used
                 // the context already such as in text filter in page title.
-                debugging("Coding problem: unsupported modification of PAGE->context from {$current} to {$context->contextlevel}");
+                // This is explicitly allowed for webservices though which may
+                // call "external_api::validate_context on many contexts in a single request.
+                if (!WS_SERVER) {
+                    debugging("Coding problem: unsupported modification of PAGE->context from {$current} to {$context->contextlevel}");
+                }
             }
         }