narou u -a --backtraceでは以下のエラーメッセージが表示されました。
--gl narouやotherでもほぼ同じエラーメッセージでしたが、otherの場合はエラーが出るまでに更新確認が10%ほどまで進行していました。
C:/Ruby25-x64/lib/ruby/2.5.0/net/protocol.rb:44:in `connect_nonblock': SSL_connect SYSCALL returned=5 errno=0 state=SSLv3/TLS write client hello (OpenSSL::SSL::SSLError)
from C:/Ruby25-x64/lib/ruby/2.5.0/net/protocol.rb:44:in `ssl_socket_connect'
from C:/Ruby25-x64/lib/ruby/2.5.0/net/http.rb:985:in `connect'
from C:/Ruby25-x64/lib/ruby/2.5.0/net/http.rb:920:in `do_start'
from C:/Ruby25-x64/lib/ruby/2.5.0/net/http.rb:909:in `start'
from C:/Ruby25-x64/lib/ruby/2.5.0/open-uri.rb:337:in `open_http'
from C:/Ruby25-x64/lib/ruby/2.5.0/open-uri.rb:755:in `buffer_open'
from C:/Ruby25-x64/lib/ruby/2.5.0/open-uri.rb:226:in `block in open_loop'
from C:/Ruby25-x64/lib/ruby/2.5.0/open-uri.rb:224:in `catch'
from C:/Ruby25-x64/lib/ruby/2.5.0/open-uri.rb:224:in `open_loop'
from C:/Ruby25-x64/lib/ruby/2.5.0/open-uri.rb:165:in `open_uri'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/open_uri_redirections-0.2.1/lib/open-uri/redirections_patch.rb:55:in `open_uri'
from C:/Ruby25-x64/lib/ruby/2.5.0/open-uri.rb:735:in `open'
from C:/Ruby25-x64/lib/ruby/2.5.0/open-uri.rb:35:in `open'
from C:/Ruby25-x64/lib/ruby/2.5.0/open-uri.rb:46:in `open'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/downloader.rb:728:in `get_toc_source'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/downloader.rb:763:in `get_latest_table_of_contents'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/downloader.rb:349:in `run_download'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/downloader.rb:332:in `start_download'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/command/update.rb:182:in `block in execute'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/command/update.rb:157:in `each'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/command/update.rb:157:in `each_with_index'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/command/update.rb:157:in `execute'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/commandbase.rb:125:in `execute!'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/commandbase.rb:134:in `execute!'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/commandline.rb:29:in `run'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/commandline.rb:43:in `run!'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/narou.rb:50:in `block in <top (required)>'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/lib/backtracer.rb:16:in `capture'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/narou.rb:49:in `<top (required)>'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/bin/narou:13:in `require_relative'
from C:/Ruby25-x64/lib/ruby/gems/2.5.0/gems/narou-3.5.0.1/bin/narou:13:in `<top (required)>'
from C:/Ruby25-x64/bin/narou:23:in `load'
from C:/Ruby25-x64/bin/narou:23:in `<main>'