diff --git a/lib/connection_tester.rb b/lib/connection_tester.rb
index 0783b3a93..e226d53fa 100644
--- a/lib/connection_tester.rb
+++ b/lib/connection_tester.rb
@@ -1,7 +1,9 @@
 
 class ConnectionTester
-  NODEINFO_SCHEMA   = "http://nodeinfo.diaspora.software/ns/schema/1.0"
-  NODEINFO_FRAGMENT = "/.well-known/nodeinfo"
+  include Diaspora::Logging
+
+  NODEINFO_SCHEMA   = "http://nodeinfo.diaspora.software/ns/schema/1.0".freeze
+  NODEINFO_FRAGMENT = "/.well-known/nodeinfo".freeze
 
   class << self
     # Test the reachability of a server by the given HTTP/S URL.
@@ -74,7 +76,7 @@ class ConnectionTester
   rescue URI::InvalidURIError => e
     raise AddressFailure, e.message
   rescue StandardError => e
-    raise Failure, e.inspect
+    unexpected_error(e)
   end
 
   # Perform the DNS query, the IP address will be stored in the result
@@ -84,7 +86,7 @@ class ConnectionTester
   rescue SocketError => e
     raise DNSFailure, "'#{@uri.host}' - #{e.message}"
   rescue StandardError => e
-    raise Failure, e.inspect
+    unexpected_error(e)
   end
 
   # Perform a HTTP GET request to determine the following information
@@ -113,7 +115,7 @@ class ConnectionTester
   rescue ArgumentError, FaradayMiddleware::RedirectLimitReached, Faraday::ClientError => e
     raise HTTPFailure, e.message
   rescue StandardError => e
-    raise Failure, e.inspect
+    unexpected_error(e)
   end
 
   # Try to find out the version of the other servers software.
@@ -130,7 +132,7 @@ class ConnectionTester
   rescue Faraday::ResourceNotFound, JSON::JSONError => e
     raise NodeInfoFailure, e.message[0..255].encode(Encoding.default_external, undef: :replace)
   rescue StandardError => e
-    raise Failure, e.inspect
+    unexpected_error(e)
   end
 
   private
@@ -192,6 +194,11 @@ class ConnectionTester
     @result.software_version = "#{sw.fetch('name')} #{sw.fetch('version')}"
   end
 
+  def unexpected_error(error)
+    logger.error "unexpected error: #{error.class}: #{error.message}\n#{error.backtrace.first(15).join("\n")}"
+    raise Failure, error.inspect
+  end
+
   class Failure < StandardError
   end