Since I upgraded sogo from nightly version 5.5.1.20220228-1 to 5.5.1.20220309-1 all users got an "unhandled error" on login.

I located an error in sogo.log:

Mar 11 01:43:33 sogod [412037]: [ERROR] <0x0x5654475f57f0[GCSSessionsFolder]> -[GCSSessionsFolder writeRecordForEntryWithID:value:creationDate:lastSeenDate:]: cannot write record: <MySQL4Exception: 0x5654476243c0> NAME:ExecutionFailed REASON:Data too long for column 'c_value' at row 1

and after enlarging the column c_value from 255 to 4096 with alter table sogo_sessions_folder modify c_value varchar(4096) not null; another error appeared in nginx/error.log:

2022/03/11 08:49:50 [error] 424133#424133: *4 upstream sent too big header while reading response header from upstream, client: **.***.***.*, server: _, request: "POST /SOGo/connect HTTP/2.0", upstream: "http://127.0.0.1:20000/SOGo/connect", host: "mail.****.**", referrer: "https://mail.****.**/SOGo/"

After invertigation on this error I inserted 3 lines with proxy buffers in the /etc/nginx/templates/sogo.tmpl:

location ^~ /SOGo {
    include /etc/nginx/templates/hsts.tmpl;

    proxy_pass http://127.0.0.1:20000;

    # 2022-11-03 error sogo login
    proxy_buffer_size          128k;
    proxy_buffers              4 256k;
    proxy_busy_buffers_size    256k;

    # forward user's IP address
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $host;

After that the login works again but I don't know if this solution was optimal.