OmniFocus Seafile Webdav 500 interval server error

Hi,
I use omnifocus and sync the content using Seafile. It worked fine until today…After re-synced the whole database, the app raise the error “Unable to synchronize database with server” with server returned 500 in response to a request to “PUT /seafdav/…”.
I tried different methods/settings (both nginx and seasfile), but the problem has not been solved.
So I digged into the container (docker exec), searched the /shared/seafile/logs/seafdav.log, and found the following error message:

2021-10-26 07:10:53.005 - <140193947961088> wsgidav.wsgidav_app         INFO    :  127.0.0.1 - xxx@xxx.com - [2021-10-26 07:10:53] "PUT /app/OF/OmniFocus.ofocus-copy-in-progress-izn_7yTteyA/versioned_perspectives.capability" length=418, elap=3.893sec -> 201 Created 
2021-10-26 07:10:53.515 - <140193973139200> wsgidav.wsgidav_app         INFO    :  127.0.0.1 - ionx@qq.com - [2021-10-26 07:10:53] "PUT /app/OF/OmniFocus.ofocus-copy-in-progress-izn_7yTteyA/unknown_element_import.capability" length=418, elap=4.393sec -> 201 Created 
2021-10-26 07:10:54.063 - <140193964746496> wsgidav.error_printer       ERROR   :  Caught HTTPRequestException(HTTP_INTERNAL_ERROR) 
Traceback (most recent call last): 
  File "/opt/seafile/seafile-pro-server-8.0.11/seahub/thirdpart/wsgidav/seafile_dav_provider.py", line 438, in create_empty_resource 
    seafile_api.post_empty_file(self.repo.id, self.rel_path, name, self.username) 
  File "/opt/seafile/seafile-pro-server-8.0.11/seafile/lib/python3.6/site-packages/seaserv/api.py", line 299, in post_empty_file 
    return seafserv_threaded_rpc.post_empty_file(repo_id, parent_dir, 
  File "/opt/seafile/seafile-pro-server-8.0.11/seafile/lib/python3.6/site-packages/pysearpc/client.py", line 128, in newfunc 
    return fret(ret_str) 
  File "/opt/seafile/seafile-pro-server-8.0.11/seafile/lib/python3.6/site-packages/pysearpc/client.py", line 12, in _fret_int 
    raise SearpcError(dicts['err_msg']) 
pysearpc.common.SearpcError: Concurrent update 
 
During handling of the above exception, another exception occurred: 
 
Traceback (most recent call last): 
  File "/opt/seafile/seafile-pro-server-8.0.11/seahub/thirdpart/wsgidav/error_printer.py", line 52, in __call__ 
    for v in app_iter: 
  File "/opt/seafile/seafile-pro-server-8.0.11/seahub/thirdpart/wsgidav/request_resolver.py", line 213, in __call__ 
    for v in app_iter: 
  File "/opt/seafile/seafile-pro-server-8.0.11/seahub/thirdpart/wsgidav/request_server.py", line 126, in __call__ 
    app_iter = provider.custom_request_handler(environ, start_response, method) 
  File "/opt/seafile/seafile-pro-server-8.0.11/seahub/thirdpart/wsgidav/dav_provider.py", line 1525, in custom_request_handler 
    return default_handler(environ, start_response) 
  File "/opt/seafile/seafile-pro-server-8.0.11/seahub/thirdpart/wsgidav/request_server.py", line 780, in do_PUT 
    res = parentRes.create_empty_resource(util.get_uri_name(path)) 
  File "/opt/seafile/seafile-pro-server-8.0.11/seahub/thirdpart/wsgidav/seafile_dav_provider.py", line 443, in create_empty_resource 
    raise DAVError(HTTP_INTERNAL_ERROR, e.msg) 
wsgidav.dav_error.DAVError: DAVError(500 Internal Server Error: Concurrent update) 
 
2021-10-26 07:10:54.064 - <140193964746496> wsgidav.error_printer       ERROR   :  e.src_exception: 
None 
2021-10-26 07:10:54.064 - <140193964746496> wsgidav.wsgidav_app         INFO    :  127.0.0.1 - xxx@xxx.com  - [2021-10-26 07:10:54] "PUT /app/OF/OmniFocus.ofocus-copy-in-progress-izn_7yTteyA/active_object_hidden_dates.capability" length=422, elap=3.651sec -> 500 Internal Server Error 

I am not sure if it is a bug of seafile? As I am now sync to Omni Group server, and everything is fine.