1 files changed, 3 insertions, 0 deletions
diff --git a/src/Olm.cpp b/src/Olm.cpp
index 028095a6..4ccf8ab9 100644
--- a/src/Olm.cpp
+++ b/src/Olm.cpp
@@ -890,12 +890,15 @@ decryptEvent(const MegolmSessionIndex &index,
         std::string msg_str;
         try {
                 auto session = cache::client()->getInboundMegolmSession(index);
+
                 auto res =
                   olm::client()->decrypt_group_message(session.get(), event.content.ciphertext);
                 msg_str = std::string((char *)res.data.data(), res.data.size());
         } catch (const lmdb::error &e) {
                 return {DecryptionErrorCode::DbError, e.what(), std::nullopt};
         } catch (const mtx::crypto::olm_exception &e) {
+                if (e.error_code() == mtx::crypto::OlmErrorCode::UNKNOWN_MESSAGE_INDEX)
+                        return {DecryptionErrorCode::MissingSessionIndex, e.what(), std::nullopt};
                 return {DecryptionErrorCode::DecryptionFailed, e.what(), std::nullopt};
         }