Thanks for getting back Amy.
Desktop app, need to check on the Mac version.
Had a look at the logs just now, greping for the Mac users id:
grep 8dswyysofib77ji8ehm6x35cea /opt/mattermost/logs/mattermost.log
{"level":"error","ts":1579770356.6272483,"caller":"mlog/log.go:174","msg":"Unable to upload file(s). Error reading or parsing request data.","path":"/api/v4/files","request_id":"wwm6g4jnjt8w8bdmpwrmye6r6o","ip_addr":"94.118.31.188","user_id":"8dswyysofib77ji8ehm6x35cea","method":"POST","err_where":"uploadFileMultipartLegacy","http_code":500,"err_details":"client disconnected"}
{"level":"error","ts":1580314194.8105474,"caller":"mlog/log.go:174","msg":"Unable to upload file(s). Error reading or parsing request data.","path":"/api/v4/files","request_id":"1hjqeqrftjrc7f4z6xdtx4ujtr","ip_addr":"12.15.241.25","user_id":"8dswyysofib77ji8ehm6x35cea","method":"POST","err_where":"uploadFileMultipartLegacy","http_code":500,"err_details":"client disconnected"}
{"level":"error","ts":1581563833.253907,"caller":"mlog/log.go:174","msg":"Failed to upgrade websocket connection","path":"/api/v4/websocket","request_id":"ao4hw9eja7dt9rmzg86q4pa9yw","ip_addr":"86.181.126.192","user_id":"8dswyysofib77ji8ehm6x35cea","method":"GET","err_where":"connect","http_code":500,"err_details":""}
{"level":"error","ts":1581936358.5947247,"caller":"mlog/log.go:174","msg":"Failed to upgrade websocket connection","path":"/api/v4/websocket","request_id":"ywfnnc8xfid89qznyajymtrqfr","ip_addr":"62.28.38.225","user_id":"8dswyysofib77ji8ehm6x35cea","method":"GET","err_where":"connect","http_code":500,"err_details":""}
{"level":"error","ts":1582083118.1039333,"caller":"mlog/log.go:174","msg":"Failed to upgrade websocket connection","path":"/api/v4/websocket","request_id":"5tz8oho7opdbmemzgqjc1stska","ip_addr":"86.175.39.62","user_id":"8dswyysofib77ji8ehm6x35cea","method":"GET","err_where":"connect","http_code":500,"err_details":""}
{"level":"error","ts":1582168630.290813,"caller":"mlog/log.go:174","msg":"Failed to upgrade websocket connection","path":"/api/v4/websocket","request_id":"7qzk66qjbty39qdnf63htimdzy","ip_addr":"86.175.39.62","user_id":"8dswyysofib77ji8ehm6x35cea","method":"GET","err_where":"connect","http_code":500,"err_details":""}
{"level":"error","ts":1582218686.6295214,"caller":"mlog/log.go:174","msg":"Failed to upgrade websocket connection","path":"/api/v4/websocket","request_id":"sd8tqsjk9pgr8ehs3i7sua36zr","ip_addr":"185.192.70.106","user_id":"8dswyysofib77ji8ehm6x35cea","method":"GET","err_where":"connect","http_code":500,"err_details":""}
{"level":"error","ts":1583266462.5474863,"caller":"mlog/log.go:174","msg":"Encountered an error retrieving the status","path":"/api/v4/users/status/ids","request_id":"16nmw53rmpdoufh37mwocbknia","ip_addr":"185.192.70.12","user_id":"8dswyysofib77ji8ehm6x35cea","method":"POST","err_where":"SqlStatusStore.GetByIds","http_code":500,"err_details":"dial tcp [::1]:5432: connect: connection refused"}
{"level":"error","ts":1583266522.537645,"caller":"mlog/log.go:174","msg":"Encountered an error retrieving the status","path":"/api/v4/users/status/ids","request_id":"opzdojpgaid5j88nha6f76b3hr","ip_addr":"185.192.70.12","user_id":"8dswyysofib77ji8ehm6x35cea","method":"POST","err_where":"SqlStatusStore.GetByIds","http_code":500,"err_details":"dial tcp [::1]:5432: connect: connection refused"}
Does this provide a hint?