This seems similar to https://forums.sabnzbd.org/viewtopic.php?t=11252, although a workaround was added for that issue.
------------------------------------------------------------------------------------------
This is logged continually to sabnzbd.error.log
TypeError: can't concat int to bytes
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python3.8/threading.py", line 932, in _bootstrap_inner
    self.run()
  File "/usr/share/sabnzbdplus/sabnzbd/downloader.py", line 610, in run
    nzo.update_download_stats(BPSMeter.do.bps, server.id, bytes_received)
  File "/usr/share/sabnzbdplus/sabnzbd/nzbstuff.py", line 716, in update_download_stats
    self.servercount[serverid] += bytes
------------------------------------------------------------------------------------------
This is logged continually to error.log
2020-06-02 20:37:38,126::INFO::[sabnzbdplus:1096] --------------------------------
2020-06-02 20:37:38,127::INFO::[sabnzbdplus:1097] sabnzbdplus-3.0.0-develop (rev=unknown)
2020-06-02 20:37:38,127::INFO::[sabnzbdplus:1098] Full executable path = /usr/bin/sabnzbdplus
2020-06-02 20:37:38,128::INFO::[sabnzbdplus:1108] Platform = posix
2020-06-02 20:37:38,128::INFO::[sabnzbdplus:1109] Python-version = 3.8.2 (default, Apr 27 2020, 15:53:34)
[GCC 9.3.0]
2020-06-02 20:37:38,128::INFO::[sabnzbdplus:1110] Arguments = /usr/bin/sabnzbdplus --daemon --pidfile /var/run/sabnzbdplus/pid
2020-06-02 20:37:38,128::INFO::[sabnzbdplus:1114] Not inside a docker container
2020-06-02 20:37:38,129::INFO::[sabnzbdplus:1117] Preferred encoding = UTF-8
2020-06-02 20:37:38,129::INFO::[sabnzbdplus:1124] SSL version = OpenSSL 1.1.1f  31 Mar 2020
2020-06-02 20:37:38,129::INFO::[sabnzbdplus:1171] Using INI file /home/ash/.sabnzbd/sabnzbd.ini
2020-06-02 20:37:38,136::INFO::[postproc:129] Loading postproc queue
2020-06-02 20:37:39,458::INFO::[__init__:912] [N/A] /home/ash/.sabnzbd/admin/Rating.sab missing
2020-06-02 20:37:39,459::INFO::[scheduler:197] Setting schedule for midnight BPS reset
2020-06-02 20:37:39,459::INFO::[__init__:340] All processes started
2020-06-02 20:37:39,460::INFO::[sabnzbdplus:278] Template location for Glitter is /usr/share/sabnzbdplus/interfaces/Glitter
2020-06-02 20:37:39,460::INFO::[sabnzbdplus:278] Template location for Config is /usr/share/sabnzbdplus/interfaces/Config
2020-06-02 20:37:39,466::INFO::[config:852] Writing settings to INI file /home/ash/.sabnzbd/sabnzbd.ini
2020-06-02 20:37:39,499::INFO::[sabnzbdplus:379] SABYenc module (v4.0.1)... found!
2020-06-02 20:37:39,500::INFO::[sabnzbdplus:391] Cryptography module (v2.8)... found!
2020-06-02 20:37:39,500::INFO::[sabnzbdplus:394] par2 binary... found (/usr/bin/par2)
2020-06-02 20:37:39,500::INFO::[sabnzbdplus:406] UNRAR binary... found (/usr/bin/unrar)
2020-06-02 20:37:39,500::INFO::[sabnzbdplus:414] UNRAR binary version 5.61
2020-06-02 20:37:39,501::INFO::[sabnzbdplus:421] unzip binary... found (/usr/bin/unzip)
2020-06-02 20:37:39,501::INFO::[sabnzbdplus:426] 7za binary... found (/usr/bin/7za)
2020-06-02 20:37:39,501::INFO::[sabnzbdplus:432] nice binary... found (/usr/bin/nice)
2020-06-02 20:37:39,501::INFO::[sabnzbdplus:436] ionice binary... found (/usr/bin/ionice)
2020-06-02 20:37:39,504::INFO::[sabnzbdplus:1324] Starting web-interface on 0.0.0.0:8080
2020-06-02 20:37:39,504::INFO::[_cplogging:219] [02/Jun/2020:20:37:39] ENGINE Bus STARTING
2020-06-02 20:37:39,509::INFO::[_cplogging:219] [02/Jun/2020:20:37:39] ENGINE Started monitor thread '_TimeoutMonitor'.
2020-06-02 20:37:39,696::INFO::[_cplogging:219] [02/Jun/2020:20:37:39] ENGINE Serving on http://0.0.0.0:8080
2020-06-02 20:37:39,697::INFO::[_cplogging:219] [02/Jun/2020:20:37:39] ENGINE Bus STARTED
2020-06-02 20:37:39,698::INFO::[sabnzbdplus:1366] Starting sabnzbdplus-3.0.0-develop
2020-06-02 20:37:39,714::INFO::[postproc:219] Completed Download Folder /mnt/data/Downloads/complete is not on FAT
2020-06-02 20:37:39,715::INFO::[dirscanner:370] Dirscanner starting up
2020-06-02 20:37:39,723::INFO::[urlgrabber:83] URLGrabber starting up
2020-06-02 20:37:39,725::INFO::[zconfig:76] Bonjour/ZeroConfig does not support "localhost"
2020-06-02 20:37:40,739::INFO::[downloader:491] 1@blah.com: Initiating connection
2020-06-02 20:37:40,808::INFO::[happyeyeballs:146] Quickest IP address for blah.com (port 563, ssl 1, preferipv6 True) is None
2020-06-02 20:37:40,811::INFO::[downloader:491] 2@blah.com: Initiating connection
2020-06-02 20:37:40,812::INFO::[downloader:491] 3@blah.com: Initiating connection
2020-06-02 20:37:40,814::INFO::[downloader:491] 4@blah.com: Initiating connection
2020-06-02 20:37:40,815::INFO::[downloader:491] 5@blah.com: Initiating connection
2020-06-02 20:37:40,817::INFO::[downloader:491] 6@blah.com: Initiating connection
2020-06-02 20:37:40,818::INFO::[downloader:491] 7@blah.com: Initiating connection
2020-06-02 20:37:40,820::INFO::[downloader:491] 8@blah.com: Initiating connection
2020-06-02 20:37:40,822::INFO::[downloader:491] 9@blah.com: Initiating connection
2020-06-02 20:37:40,823::INFO::[downloader:491] 10@blah.com: Initiating connection
2020-06-02 20:37:40,825::INFO::[downloader:491] 11@blah.com: Initiating connection
2020-06-02 20:37:40,826::INFO::[downloader:491] 12@blah.com: Initiating connection
2020-06-02 20:37:40,828::INFO::[downloader:491] 13@blah.com: Initiating connection
2020-06-02 20:37:40,830::INFO::[downloader:491] 14@blah.com: Initiating connection
2020-06-02 20:37:40,831::INFO::[downloader:491] 15@blah.com: Initiating connection
2020-06-02 20:37:40,833::INFO::[downloader:491] 16@blah.com: Initiating connection
2020-06-02 20:37:40,834::INFO::[downloader:491] 17@blah.com: Initiating connection
2020-06-02 20:37:40,836::INFO::[downloader:491] 18@blah.com: Initiating connection
2020-06-02 20:37:40,837::INFO::[downloader:491] 19@blah.com: Initiating connection
2020-06-02 20:37:40,839::INFO::[downloader:491] 20@blah.com: Initiating connection
2020-06-02 20:37:41,007::INFO::[newswrapper:104] 2@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,008::INFO::[newswrapper:104] 3@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,013::INFO::[newswrapper:104] 4@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,015::INFO::[newswrapper:104] 1@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,019::INFO::[newswrapper:104] 6@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,022::INFO::[newswrapper:104] 5@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,030::INFO::[newswrapper:104] 10@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,034::INFO::[newswrapper:104] 9@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,035::INFO::[newswrapper:104] 7@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,035::INFO::[newswrapper:104] 8@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,036::INFO::[newswrapper:104] 14@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,039::INFO::[newswrapper:104] 15@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,040::INFO::[newswrapper:104] 12@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,042::INFO::[newswrapper:104] 11@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,044::INFO::[newswrapper:104] 13@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,052::INFO::[newswrapper:104] 17@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,053::INFO::[newswrapper:104] 16@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,057::INFO::[newswrapper:104] 18@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,065::INFO::[newswrapper:104] 19@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,068::INFO::[newswrapper:104] 20@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:41,842::INFO::[downloader:491] 1@blah.com: Initiating connection
2020-06-02 20:37:41,993::INFO::[happyeyeballs:146] Quickest IP address for blah.com (port 563, ssl 1, preferipv6 True) is None
2020-06-02 20:37:41,994::INFO::[downloader:491] 2@blah.com: Initiating connection
2020-06-02 20:37:41,995::INFO::[downloader:491] 3@blah.com: Initiating connection
2020-06-02 20:37:41,997::INFO::[downloader:491] 4@blah.com: Initiating connection
2020-06-02 20:37:41,998::INFO::[downloader:491] 5@blah.com: Initiating connection
2020-06-02 20:37:42,000::INFO::[downloader:491] 6@blah.com: Initiating connection
2020-06-02 20:37:42,001::INFO::[downloader:491] 7@blah.com: Initiating connection
2020-06-02 20:37:42,003::INFO::[downloader:491] 8@blah.com: Initiating connection
2020-06-02 20:37:42,415::INFO::[newswrapper:104] 1@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:42,428::INFO::[newswrapper:104] 5@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:42,443::INFO::[newswrapper:104] 4@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:42,461::INFO::[newswrapper:104] 2@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:42,477::INFO::[newswrapper:104] 7@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:42,489::INFO::[newswrapper:104] 8@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:42,509::INFO::[newswrapper:104] 3@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:37:42,519::INFO::[newswrapper:104] 6@blah.com: Connected using TLSv1.2 (AES128-SHA)
2020-06-02 20:38:12,758::INFO::[__init__:1023] Restarting because of crashed downloader
2020-06-02 20:38:12,758::INFO::[__init__:755] [N/A] Performing SABnzbd shutdown
2020-06-02 20:38:12,758::INFO::[__init__:376] SABnzbd shutting down...
2020-06-02 20:38:12,759::INFO::[directunpacker:463] Aborting all DirectUnpackers
2020-06-02 20:38:12,759::INFO::[urlgrabber:78] URLGrabber shutting down
2020-06-02 20:38:13,759::INFO::[dirscanner:361] Dirscanner shutting down
2020-06-02 20:38:14,759::INFO::[assembler:63] Shutting down
2020-06-02 20:38:14,760::INFO::[nzbqueue:204] Saving queue
2020-06-02 20:38:16,162::INFO::[postproc:123] Saving postproc queue
2020-06-02 20:38:16,163::INFO::[__init__:440] All processes stopped
2020-06-02 20:38:16,164::INFO::[_cplogging:219] [02/Jun/2020:20:38:16] ENGINE Bus STOPPING
2020-06-02 20:38:16,167::INFO::[_cplogging:219] [02/Jun/2020:20:38:16] ENGINE HTTP Server cherrypy._cpwsgi_server.CPWSGIServer(('0.0.0.0', 8080)) shut down
2020-06-02 20:38:16,167::INFO::[_cplogging:219] [02/Jun/2020:20:38:16] ENGINE Stopped thread '_TimeoutMonitor'.
2020-06-02 20:38:16,167::INFO::[_cplogging:219] [02/Jun/2020:20:38:16] ENGINE Bus STOPPED
2020-06-02 20:38:16,168::INFO::[_cplogging:219] [02/Jun/2020:20:38:16] ENGINE Bus EXITING
2020-06-02 20:38:16,168::INFO::[_cplogging:219] [02/Jun/2020:20:38:16] ENGINE Bus EXITED
2020-06-02 20:38:16,168::INFO::[_cplogging:219] [02/Jun/2020:20:38:16] ENGINE Re-spawning /usr/bin/python3 -OO /usr/bin/sabnzbdplus --daemon --pidfile /var/run/sabnzbdplus/pid