02:06:48: ERROR[ServerThread]: ERROR: An unhandled exception occurred: Couldn't save env meta

In thread 7fb5c911c700:
/home/zat/src/minetest/src/server.cpp:134: virtual void* ServerThread::Thread(): Assertion '0' failed.
Debug stacks:
DEBUG STACK FOR THREAD 7fb5bffff700:
#0  virtual void* EmergeThread::Thread()
(Leftover data: #1  MapBlock* ServerMap::loadBlock(v3s16))
(Leftover data: #2  void ServerMap::loadBlock(std::string*, v3s16, MapSector*, bool))
(Leftover data: #3  void ItemStack::deSerialize(std::istream&, IItemDefManager*))
DEBUG STACK FOR THREAD 7fb5c891b700:
#0  virtual void* CurlFetchThread::Thread()
DEBUG STACK FOR THREAD 7fb5c911c700:
#0  virtual void* ServerThread::Thread()
(Leftover data: #1  void Server::AsyncRunStep(bool))
(Leftover data: #2  virtual void ServerMap::save(ModifiedState))
(Leftover data: #3  void Server::DenyAccess(irr::u16, const wstring&))
(Leftover data: #4  void Server::SendAccessDenied(irr::u16, const wstring&))
(Leftover data: #5  void ServerMap::loadBlock(std::string*, v3s16, MapSector*, bool))
DEBUG STACK FOR THREAD 7fb5d68c7780:
#0  int main(int, char**)
#1  Dedicated server branch
#2  void dedicated_server_loop(Server&, bool&)
(Leftover data: #3  void Server::step(float))