diff --git a/lib/server.js b/lib/server.js
index 1726578..255acd4 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -2179,8 +2179,17 @@ WalletService.prototype.signTx = function(opts, cb) {
 
       var copayer = wallet.getCopayer(self.copayerId);
 
-      if (!txp.sign(self.copayerId, opts.signatures, copayer.xPubKey))
+      if (!txp.sign(self.copayerId, opts.signatures, copayer.xPubKey)) {
+        log.warn('Error signing transaction (BAD_SIGNATURES)');
+        log.warn('Wallet id:', self.walletId);
+        log.warn('Copayer id:', self.copayerId);
+        log.warn('Client version:', self.clientVersion);
+        log.warn('Arguments:', JSON.stringify(opts));
+        log.warn('Transaction proposal:', JSON.stringify(txp));
+        var raw = txp.getBitcoreTx().uncheckedSerialize();
+        log.warn('Raw tx:', raw);
         return cb(Errors.BAD_SIGNATURES);
+      }
 
       self.storage.storeTx(self.walletId, txp, function(err) {
         if (err) return cb(err);