diff --git a/README.md b/README.md
index 1886ae4..4dd9f82 100644
--- a/README.md
+++ b/README.md
@@ -1,9 +1,6 @@
 # Untwine
 
-Untwine is software from [Hobu, Inc.](https://hobu.co) for creating [Entwine Point Tile](https://entwine.io/entwine-point-tile.html)  (EPT) 
-or [Cloud Optimized Point Cloud](https://copc.io/) (COPC) web services from [PDAL](https://pdal.io)-readable point cloud data sources. It
-provides an alternative processing approach than the [Entwine](https://entwine.io)
-software, but the output is expected to be compatible EPT/COPC.
+Untwine is software from [Hobu, Inc.](https://hobu.co) for creating [Cloud Optimized Point Cloud](https://copc.io/) (COPC) web services from [PDAL](https://pdal.io)-readable point cloud data sources.
 
 
 License
@@ -54,9 +51,9 @@ Options
 
   Input files or directories containing input files. [Required]
 
-- output_dir
+- output_file
 
-  Output directory. [Required]
+  Output file. [Required]
 
 - a_srs
 
diff --git a/bu/Processor.cpp b/bu/Processor.cpp
index 7bfbcf3..c7e7d73 100644
--- a/bu/Processor.cpp
+++ b/bu/Processor.cpp
@@ -52,14 +52,12 @@ void Processor::run()
     }
     catch (const std::exception& ex)
     {
-        std::cerr << "Exception: " << ex.what() << "\n";
         m_manager.queueWithError(m_vi.octant(), ex.what());
         return;
     }
     catch (...)
     {
         std::string msg = std::string("Unexpected error processing ") + m_vi.key().toString() + ".";
-        std::cerr << "Exception: " << msg << "\n";
         m_manager.queueWithError(m_vi.octant(), msg);
         return;
     }
@@ -490,7 +488,7 @@ void Processor::createChunk(const VoxelKey& key, pdal::PointViewPtr view)
     out.write(reinterpret_cast<const char *>(chunk.data()), chunk.size());
     out.close();
     if (!out)
-        throw FatalError("Failure writing to '" + m_b.opts.outputName + "'.");
+        throw FatalError("Failure writing to file '" + m_b.opts.outputName + "'.");
 }
 
 void Processor::fillPointBuf(pdal::PointRef& point, std::vector<char>& buf,
diff --git a/bu/PyramidManager.cpp b/bu/PyramidManager.cpp
index 36748c1..54345be 100644
--- a/bu/PyramidManager.cpp
+++ b/bu/PyramidManager.cpp
@@ -79,7 +79,8 @@ void PyramidManager::run()
 
             if (m_error.size())
             {
-                std::cerr << "Exception: " << m_error << "\n";
+                lock.unlock();
+                m_pool.join();
                 throw FatalError(m_error);
             }
         }
diff --git a/epf/Writer.cpp b/epf/Writer.cpp
index 40175c5..3e25584 100644
--- a/epf/Writer.cpp
+++ b/epf/Writer.cpp
@@ -153,7 +153,7 @@ void Writer::run()
         std::lock_guard<std::mutex> lock(m_mutex);
         if (!out)
         {
-            m_pool.setError("Failure writing to '" + path(wd.key) + "'.");
+            m_pool.setError("Failure writing to file '" + path(wd.key) + "'.");
             m_stop = true;
         }
         else
diff --git a/untwine/Untwine.cpp b/untwine/Untwine.cpp
index 03038fa..e398bed 100644
--- a/untwine/Untwine.cpp
+++ b/untwine/Untwine.cpp
@@ -75,7 +75,7 @@ bool handleOptions(pdal::StringList& arglist, Options& options)
             std::cout << "untwine version (" << UNTWINE_VERSION << ")\n";
         if (help)
         {
-            std::cout << "Usage: untwine [output file/directory] <options>\n";
+            std::cout << "Usage: untwine output file <options>\n";
             programArgs.dump(std::cout, 2, 80);
         }
         if (help || version)
@@ -83,6 +83,14 @@ bool handleOptions(pdal::StringList& arglist, Options& options)
 
         programArgs.parse(arglist);
 
+        // Make sure the output file can be opened so that we can provide an early error if
+        // there's a problem.
+        std::ofstream tmp(os::toNative(options.outputName), std::ios::out | std::ios::binary);
+        if (!tmp)
+            throw FatalError("Can't open file '" + options.outputName + "' for output");
+        tmp.close();
+        pdal::FileUtils::deleteFile(options.outputName);
+
         if (!tempArg->set())
         {
             options.tempDir = options.outputName + "_tmp";