This problem prevents user login with SSL to the Dovecot IMAP server. The errors in the journal look like this:
... imap-login: Error: Failed to initialize SSL server context: Can't load SSL certificate (ssl_cert setting): error:25066067:DSO support routines:dlfcn_load:could not load the shared library: filename(libproviders.so): libproviders.so: cannot open shared object file: No such file or directory, error:25070067:DSO support routines:DSO_load:could not load the shared library, error:0E07506E:configuration file routines:module_load_dso:error loading dso: module=providers, path=providers, error:0E076071:configuration file routines:module_run:unknown module name: module=providers: ...
A fix/workaround was found at Bug#1011051: libssl3: upgrade to libssl3 broke my dovecot setup. By commenting out the line “providers = provider_sect” in the configuration file “/etc/ssl/openssl.cnf”, the service is restored. Hope this will be resolved properly in the near future.