Change file timestamps if necessary because ZIP does not support timestamps before 1980. Fixes #1360.

gns3server/handlers/api/controller/project_handler.py

@@ -304,8 +304,8 @@ class ProjectHandler:
                 yield from response.write_eof()
         # Will be raise if you have no space left or permission issue on your temporary directory
         # RuntimeError: something was wrong during the zip process
-        except (OSError, RuntimeError) as e:
-            raise aiohttp.web.HTTPNotFound(text="Can't export project: {}".format(str(e)))
+        except (ValueError, OSError, RuntimeError) as e:
+            raise aiohttp.web.HTTPNotFound(text="Cannot export project: {}".format(str(e)))
 
     @Route.post(
         r"/projects/{project_id}/import",