diff --git a/api/jsep.cc b/api/jsep.cc
index 5fdc8905c7..ddb39b6181 100644
--- a/api/jsep.cc
+++ b/api/jsep.cc
@@ -21,6 +21,23 @@ size_t SessionDescriptionInterface::RemoveCandidates(
   return 0;
 }
 
+void CreateSessionDescriptionObserver::OnFailure(RTCError error) {
+  OnFailure(error.message());
+}
+
+void CreateSessionDescriptionObserver::OnFailure(const std::string& error) {
+  OnFailure(RTCError(RTCErrorType::INTERNAL_ERROR, std::string(error)));
+}
+
+void SetSessionDescriptionObserver::OnFailure(RTCError error) {
+  std::string message(error.message());
+  OnFailure(message);
+}
+
+void SetSessionDescriptionObserver::OnFailure(const std::string& error) {
+  OnFailure(RTCError(RTCErrorType::INTERNAL_ERROR, std::string(error)));
+}
+
 const char SessionDescriptionInterface::kOffer[] = "offer";
 const char SessionDescriptionInterface::kPrAnswer[] = "pranswer";
 const char SessionDescriptionInterface::kAnswer[] = "answer";
diff --git a/api/jsep.h b/api/jsep.h
index cf8aeb0cb4..86f4162f84 100644
--- a/api/jsep.h
+++ b/api/jsep.h
@@ -28,7 +28,6 @@
 
 #include "absl/types/optional.h"
 #include "api/rtc_error.h"
-#include "rtc_base/deprecation.h"
 #include "rtc_base/ref_count.h"
 #include "rtc_base/system/rtc_export.h"
 
@@ -223,9 +222,11 @@ class RTC_EXPORT CreateSessionDescriptionObserver
   // error code and a string.
   // RTCError is non-copyable, so it must be passed using std::move.
   // Earlier versions of the API used a string argument. This version
-  // is removed; its functionality was the same as passing
-  // error.message.
-  virtual void OnFailure(RTCError error) = 0;
+  // is deprecated; in order to let clients remove the old version, it has a
+  // default implementation. If both versions are unimplemented, the
+  // result will be a runtime error (stack overflow). This is intentional.
+  virtual void OnFailure(RTCError error);
+  virtual void OnFailure(const std::string& error);
 
  protected:
   ~CreateSessionDescriptionObserver() override = default;
@@ -236,7 +237,9 @@ class RTC_EXPORT SetSessionDescriptionObserver : public rtc::RefCountInterface {
  public:
   virtual void OnSuccess() = 0;
   // See description in CreateSessionDescriptionObserver for OnFailure.
-  virtual void OnFailure(RTCError error) = 0;
+  virtual void OnFailure(RTCError error);
+
+  virtual void OnFailure(const std::string& error);
 
  protected:
   ~SetSessionDescriptionObserver() override = default;