[nqk]

I would like to report a bug.

Some books, which worked fine with Version 5.6, can't be loaded.

Traceback (most recent call last):
  File "/usr/lib/calibre/calibre/srv/jobs.py", line 44, in run
    result = func()
  File "/usr/lib/calibre/calibre/utils/ipc/simple_worker.py", line 251, in fork_job
    :return: A dictionary with the keys result and stdout_stderr. result is the
  File "/usr/lib/calibre/calibre/utils/ipc/simple_worker.py", line 176, in run_job
    no_output=False, heartbeat=None, abort=None, module_is_source_code=False
  File "/usr/lib/calibre/calibre/utils/ipc/simple_worker.py", line 115, in communicate
    if cw.tb:
calibre.utils.ipc.simple_worker.WorkerError: Failed to connect to worker process