diff --git a/platformio/commands/home/rpc/handlers/piocore.py b/platformio/commands/home/rpc/handlers/piocore.py
index ef290ea3..07809171 100644
--- a/platformio/commands/home/rpc/handlers/piocore.py
+++ b/platformio/commands/home/rpc/handlers/piocore.py
@@ -19,6 +19,7 @@ import os
 import sys
 from io import BytesIO, StringIO
 
+import click
 import jsonrpc  # pylint: disable=import-error
 from twisted.internet import threads  # pylint: disable=import-error
 
@@ -102,7 +103,22 @@ class PIOCoreRPC(object):
         text = ("%s\n\n%s" % (out, err)).strip()
         if code != 0:
             raise Exception(text)
-        return json.loads(out) if json_output else text
+        if not json_output:
+            return text
+        try:
+            return json.loads(out)
+        except ValueError as e:
+            click.secho("%s => `%s`" % (e, out), fg="red", err=True)
+            # if PIO Core prints unhandled warnings
+            for line in out.split("\n"):
+                line = line.strip()
+                if not line:
+                    continue
+                try:
+                    return json.loads(line)
+                except ValueError:
+                    pass
+            raise e
 
     @staticmethod
     def _call_errback(failure):
diff --git a/platformio/commands/lib.py b/platformio/commands/lib.py
index c66dc77b..cdc3d2cc 100644
--- a/platformio/commands/lib.py
+++ b/platformio/commands/lib.py
@@ -21,6 +21,7 @@ import click
 import semantic_version
 
 from platformio import exception, util
+from platformio.commands import PlatformioCLI
 from platformio.compat import dump_json_to_unicode
 from platformio.managers.lib import (LibraryManager, get_builtin_libs,
                                      is_builtin_lib)
@@ -89,6 +90,7 @@ def cli(ctx, **options):
                                         get_project_global_lib_dir(),
                                         ctx.invoked_subcommand)
 
+    in_silence = PlatformioCLI.in_silence()
     ctx.meta[CTX_META_PROJECT_ENVIRONMENTS_KEY] = options['environment']
     ctx.meta[CTX_META_INPUT_DIRS_KEY] = storage_dirs
     ctx.meta[CTX_META_STORAGE_DIRS_KEY] = []
@@ -101,7 +103,7 @@ def cli(ctx, **options):
             libdeps_dir = get_project_libdeps_dir()
         config = ProjectConfig.get_instance(join(storage_dir,
                                                  "platformio.ini"))
-        config.validate(options['environment'])
+        config.validate(options['environment'], silent=in_silence)
         for env in config.envs():
             if options['environment'] and env not in options['environment']:
                 continue
@@ -261,6 +263,7 @@ def lib_update(ctx, libraries, only_check, dry_run, json_output):
 @click.option("--json-output", is_flag=True)
 @click.pass_context
 def lib_list(ctx, json_output):
+    print("hello")
     storage_dirs = ctx.meta[CTX_META_STORAGE_DIRS_KEY]
     json_result = {}
     for storage_dir in storage_dirs: