Whatsapp Bridge "Error /syncing, waiting 10 seconds: failed to GET /_matrix/client/r0/sync..."

[jsddsfoh]

Hello,

I've succesfully setup server and bridge, I can chat with the bot and got "This room has been registered as your bridge management/status room. Send help to get a list of commands." Also, i got answer when I write help. I've not logged in to whatsapp yet, will do this after move whatsapp to another device.

The problem is, I'm getting error log etries in in /matrix/mautrix-whatsapp/data/logs/<filename>.log every 10 seconds:

[Jan 12, 2021 23:37:56] [Crypto/Bot/DEBUG] GET http://matrix-synapse:8008/_matrix/client/r0/sync?filter=0&timeout=30000
[Jan 12, 2021 23:37:56] [Crypto/ERROR] Error /syncing, waiting 10 seconds: failed to GET /_matrix/client/r0/sync: M_UNKNOWN (HTTP 500): Internal server error
[Jan 12, 2021 23:38:06] [Crypto/Bot/DEBUG] GET http://matrix-synapse:8008/_matrix/client/r0/sync?filter=0&timeout=30000
[Jan 12, 2021 23:38:06] [Crypto/ERROR] Error /syncing, waiting 10 seconds: failed to GET /_matrix/client/r0/sync: M_UNKNOWN (HTTP 500): Internal server error
[Jan 12, 2021 23:38:16] [Crypto/Bot/DEBUG] GET http://matrix-synapse:8008/_matrix/client/r0/sync?filter=0&timeout=30000
[Jan 12, 2021 23:38:16] [Crypto/ERROR] Error /syncing, waiting 10 seconds: failed to GET /_matrix/client/r0/sync: M_UNKNOWN (HTTP 500): Internal server error

Can someone help? I hope it's not because I disabled https... Can not try, there is already a proxy on another machine.

I've setup encryption according #451 and heres my vars.yml, excluding the default part (no SSL in this setup, running behind proxy which does it):

matrix_synapse_report_stats: true
matrix_client_element_enabled: false
matrix_ssl_retrieval_method: none
matrix_nginx_proxy_https_enabled: false
matrix_nginx_proxy_access_log_enabled: false
matrix_synapse_max_upload_size_mb: 200
matrix_mautrix_whatsapp_configuration_extension_yaml: |
  bridge:
    initial_chat_sync_count: 10000
    initial_history_fill_count: 200000000000
    initial_history_disable_notifications: true
    recovery_chat_sync_limit: -1
    recovery_history_backfill: true
    sync_max_chat_age: 259200000
    encryption:
      allow: true
      default: true
matrix_coturn_enabled: false
matrix_synapse_turn_uris:
<here are entries for which turn server to use>

[jsddsfoh]

Seems this is the root cause: https://github.com/matrix-org/synapse/pull/5758