diff --git a/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst b/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst
index f9d9e61..4dfb788 100644
--- a/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst
+++ b/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst
@@ -688,6 +688,8 @@
 
 It can also be used when setting mirrors definitions using the :term:`PREMIRRORS` variable.
 
+.. _crate-fetcher:
+
 Crate Fetcher (``crate://``)
 ----------------------------
 
@@ -704,6 +706,80 @@
 
    SRC_URI = "crate://crates.io/glob/0.2.11"
 
+.. _npm-fetcher:
+
+NPM Fetcher (``npm://``)
+------------------------
+
+This submodule fetches source code from an
+`NPM <https://en.wikipedia.org/wiki/Npm_(software)>`__
+Javascript package registry.
+
+The format for the :term:`SRC_URI` setting must be::
+
+   SRC_URI = "npm://some.registry.url;OptionA=xxx;OptionB=xxx;..."
+
+This fetcher supports the following parameters:
+
+-  *"package":* The NPM package name. This is a mandatory parameter.
+
+-  *"version":* The NPM package version. This is a mandatory parameter.
+
+-  *"downloadfilename":* Specifies the filename used when storing the downloaded file.
+
+-  *"destsuffix":* Specifies the directory to use to unpack the package (default: ``npm``).
+
+Note that NPM fetcher only fetches the package source itself. The dependencies
+can be fetched through the `npmsw-fetcher`_.
+
+Here is an example URL with both fetchers::
+
+   SRC_URI = " \
+       npm://registry.npmjs.org/;package=cute-files;version=${PV} \
+       npmsw://${THISDIR}/${BPN}/npm-shrinkwrap.json \
+       "
+
+See :yocto_docs:`Creating Node Package Manager (NPM) Packages
+</dev-manual/common-tasks.html#creating-node-package-manager-npm-packages>`
+in the Yocto Project manual for details about using
+:yocto_docs:`devtool <https://docs.yoctoproject.org/ref-manual/devtool-reference.html>`
+to automatically create a recipe from an NPM URL.
+
+.. _npmsw-fetcher:
+
+NPM shrinkwrap Fetcher (``npmsw://``)
+-------------------------------------
+
+This submodule fetches source code from an
+`NPM shrinkwrap <https://docs.npmjs.com/cli/v8/commands/npm-shrinkwrap>`__
+description file, which lists the dependencies
+of an NPM package while locking their versions.
+
+The format for the :term:`SRC_URI` setting must be::
+
+   SRC_URI = "npmsw://some.registry.url;OptionA=xxx;OptionB=xxx;..."
+
+This fetcher supports the following parameters:
+
+-  *"dev":* Set this parameter to ``1`` to install "devDependencies".
+
+-  *"destsuffix":* Specifies the directory to use to unpack the dependencies
+   (``${S}`` by default).
+
+Note that the shrinkwrap file can also be provided by the recipe for
+the package which has such dependencies, for example::
+
+   SRC_URI = " \
+       npm://registry.npmjs.org/;package=cute-files;version=${PV} \
+       npmsw://${THISDIR}/${BPN}/npm-shrinkwrap.json \
+       "
+
+Such a file can automatically be generated using
+:yocto_docs:`devtool <https://docs.yoctoproject.org/ref-manual/devtool-reference.html>`
+as described in the :yocto_docs:`Creating Node Package Manager (NPM) Packages
+</dev-manual/common-tasks.html#creating-node-package-manager-npm-packages>`
+section of the Yocto Project.
+
 Other Fetchers
 --------------
 
@@ -713,8 +789,6 @@
 
 -  Mercurial (``hg://``)
 
--  npm (``npm://``)
-
 -  OSC (``osc://``)
 
 -  Secure FTP (``sftp://``)
diff --git a/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst b/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst
index af4b135..3378216 100644
--- a/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst
+++ b/poky/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst
@@ -195,22 +195,45 @@
 Setting a weak default value (??=)
 ----------------------------------
 
-It is possible to use a "weaker" assignment than in the previous section
-by using the "??=" operator. This assignment behaves identical to "?="
-except that the assignment is made at the end of the parsing process
-rather than immediately. Consequently, when multiple "??=" assignments
-exist, the last one is used. Also, any "=" or "?=" assignment will
-override the value set with "??=". Here is an example::
+The weak default value of a variable is the value which that variable
+will expand to if no value has been assigned to it via any of the other
+assignment operators. The "??=" operator takes effect immediately, replacing
+any previously defined weak default value. Here is an example::
 
-   A ??= "somevalue"
-   A ??= "someothervalue"
+   W ??= "x"
+   A := "${W}" # Immediate variable expansion
+   W ??= "y"
+   B := "${W}" # Immediate variable expansion
+   W ??= "z"
+   C = "${W}"
+   W ?= "i"
 
-If ``A`` is set before the above statements are
-parsed, the variable retains its value. If ``A`` is not set, the
-variable is set to "someothervalue".
+After parsing we will have::
 
-Again, this assignment is a "lazy" or "weak" assignment because it does
-not occur until the end of the parsing process.
+   A = "x"
+   B = "y"
+   C = "i"
+   W = "i"
+
+Appending and prepending non-override style will not substitute the weak
+default value, which means that after parsing::
+
+   W ??= "x"
+   W += "y"
+
+we will have::
+
+   W = " y"
+
+On the other hand, override-style appends/prepends/removes are applied after
+any active weak default value has been substituted::
+
+   W ??= "x"
+   W:append = "y"
+
+After parsing we will have::
+
+   W = "xy"
 
 Immediate variable expansion (:=)
 ---------------------------------
diff --git a/poky/bitbake/lib/bb/fetch2/__init__.py b/poky/bitbake/lib/bb/fetch2/__init__.py
index ac55717..0fb718b 100644
--- a/poky/bitbake/lib/bb/fetch2/__init__.py
+++ b/poky/bitbake/lib/bb/fetch2/__init__.py
@@ -1097,6 +1097,8 @@
 
 def ensure_symlink(target, link_name):
     if not os.path.exists(link_name):
+        dirname = os.path.dirname(link_name)
+        bb.utils.mkdirhier(dirname)
         if os.path.islink(link_name):
             # Broken symbolic link
             os.unlink(link_name)
@@ -1220,23 +1222,21 @@
     SRC_URI as a space-separated string
     """
     fetch = Fetch([], d, cache = False, localonly = True)
-
-    dl_dir = d.getVar('DL_DIR')
     filelist = []
     for u in fetch.urls:
         ud = fetch.ud[u]
-
         if ud and isinstance(ud.method, local.Local):
+            found = False
             paths = ud.method.localpaths(ud, d)
             for f in paths:
                 pth = ud.decodedurl
-                if f.startswith(dl_dir):
-                    # The local fetcher's behaviour is to return a path under DL_DIR if it couldn't find the file anywhere else
-                    if os.path.exists(f):
-                        bb.warn("Getting checksum for %s SRC_URI entry %s: file not found except in DL_DIR" % (d.getVar('PN'), os.path.basename(f)))
-                    else:
-                        bb.warn("Unable to get checksum for %s SRC_URI entry %s: file could not be found" % (d.getVar('PN'), os.path.basename(f)))
+                if os.path.exists(f):
+                    found = True
                 filelist.append(f + ":" + str(os.path.exists(f)))
+            if not found:
+                bb.fatal(("Unable to get checksum for %s SRC_URI entry %s: file could not be found"
+                            "\nThe following paths were searched:"
+                            "\n%s") % (d.getVar('PN'), os.path.basename(f), '\n'.join(paths)))
 
     return " ".join(filelist)
 
diff --git a/poky/bitbake/lib/bb/fetch2/git.py b/poky/bitbake/lib/bb/fetch2/git.py
index 07b3d9a..4534bd7 100644
--- a/poky/bitbake/lib/bb/fetch2/git.py
+++ b/poky/bitbake/lib/bb/fetch2/git.py
@@ -738,7 +738,7 @@
         Compute the HEAD revision for the url
         """
         if not d.getVar("__BBSEENSRCREV"):
-            raise bb.fetch2.FetchError("Recipe uses a floating tag/branch without a fixed SRCREV yet doesn't call bb.fetch2.get_srcrev() (use SRCPV in PV for OE).")
+            raise bb.fetch2.FetchError("Recipe uses a floating tag/branch '%s' for repo '%s' without a fixed SRCREV yet doesn't call bb.fetch2.get_srcrev() (use SRCPV in PV for OE)." % (ud.unresolvedrev[name], ud.host+ud.path))
 
         # Ensure we mark as not cached
         bb.fetch2.get_autorev(d)
diff --git a/poky/bitbake/lib/bb/fetch2/gitsm.py b/poky/bitbake/lib/bb/fetch2/gitsm.py
index c5c23d5..c1950e4 100644
--- a/poky/bitbake/lib/bb/fetch2/gitsm.py
+++ b/poky/bitbake/lib/bb/fetch2/gitsm.py
@@ -88,7 +88,7 @@
                 subrevision[m] = module_hash.split()[2]
 
                 # Convert relative to absolute uri based on parent uri
-                if uris[m].startswith('..'):
+                if  uris[m].startswith('..') or uris[m].startswith('./'):
                     newud = copy.copy(ud)
                     newud.path = os.path.realpath(os.path.join(newud.path, uris[m]))
                     uris[m] = Git._get_repo_url(self, newud)
diff --git a/poky/bitbake/lib/bb/fetch2/local.py b/poky/bitbake/lib/bb/fetch2/local.py
index e7d1c8c..0bb987c 100644
--- a/poky/bitbake/lib/bb/fetch2/local.py
+++ b/poky/bitbake/lib/bb/fetch2/local.py
@@ -57,12 +57,6 @@
             logger.debug2("Searching for %s in paths:\n    %s" % (path, "\n    ".join(filespath.split(":"))))
             newpath, hist = bb.utils.which(filespath, path, history=True)
             searched.extend(hist)
-        if not os.path.exists(newpath):
-            dldirfile = os.path.join(d.getVar("DL_DIR"), path)
-            logger.debug2("Defaulting to %s for %s" % (dldirfile, path))
-            bb.utils.mkdirhier(os.path.dirname(dldirfile))
-            searched.append(dldirfile)
-            return searched
         return searched
 
     def need_update(self, ud, d):
@@ -78,8 +72,6 @@
             filespath = d.getVar('FILESPATH')
             if filespath:
                 locations = filespath.split(":")
-            locations.append(d.getVar("DL_DIR"))
-
             msg = "Unable to find file " + urldata.url + " anywhere. The paths that were searched were:\n    " + "\n    ".join(locations)
             raise FetchError(msg)
 
diff --git a/poky/bitbake/lib/bb/parse/parse_py/BBHandler.py b/poky/bitbake/lib/bb/parse/parse_py/BBHandler.py
index ee9bd76..6841573 100644
--- a/poky/bitbake/lib/bb/parse/parse_py/BBHandler.py
+++ b/poky/bitbake/lib/bb/parse/parse_py/BBHandler.py
@@ -178,10 +178,10 @@
 
     if s and s[0] == '#':
         if len(__residue__) != 0 and __residue__[0][0] != "#":
-            bb.fatal("There is a comment on line %s of file %s (%s) which is in the middle of a multiline expression.\nBitbake used to ignore these but no longer does so, please fix your metadata as errors are likely as a result of this change." % (lineno, fn, s))
+            bb.fatal("There is a comment on line %s of file %s:\n'''\n%s\n'''\nwhich is in the middle of a multiline expression. This syntax is invalid, please correct it." % (lineno, fn, s))
 
     if len(__residue__) != 0 and __residue__[0][0] == "#" and (not s or s[0] != "#"):
-        bb.fatal("There is a confusing multiline, partially commented expression on line %s of file %s (%s).\nPlease clarify whether this is all a comment or should be parsed." % (lineno, fn, s))
+        bb.fatal("There is a confusing multiline partially commented expression on line %s of file %s:\n%s\nPlease clarify whether this is all a comment or should be parsed." % (lineno - len(__residue__), fn, "\n".join(__residue__)))
 
     if s and s[-1] == '\\':
         __residue__.append(s[:-1])
diff --git a/poky/bitbake/lib/bb/parse/parse_py/ConfHandler.py b/poky/bitbake/lib/bb/parse/parse_py/ConfHandler.py
index b895d5b..451e68d 100644
--- a/poky/bitbake/lib/bb/parse/parse_py/ConfHandler.py
+++ b/poky/bitbake/lib/bb/parse/parse_py/ConfHandler.py
@@ -125,16 +125,21 @@
             s = f.readline()
             if not s:
                 break
+            origlineno = lineno
+            origline = s
             w = s.strip()
             # skip empty lines
             if not w:
                 continue
             s = s.rstrip()
             while s[-1] == '\\':
-                s2 = f.readline().rstrip()
+                line = f.readline()
+                origline += line
+                s2 = line.rstrip()
                 lineno = lineno + 1
                 if (not s2 or s2 and s2[0] != "#") and s[0] == "#" :
-                    bb.fatal("There is a confusing multiline, partially commented expression on line %s of file %s (%s).\nPlease clarify whether this is all a comment or should be parsed." % (lineno, fn, s))
+                    bb.fatal("There is a confusing multiline, partially commented expression starting on line %s of file %s:\n%s\nPlease clarify whether this is all a comment or should be parsed." % (origlineno, fn, origline))
+
                 s = s[:-1] + s2
             # skip comments
             if s[0] == '#':
@@ -147,8 +152,6 @@
     if oldfile:
         data.setVar('FILE', oldfile)
 
-    f.close()
-
     for f in confFilters:
         f(fn, data)
 
diff --git a/poky/bitbake/lib/bb/server/process.py b/poky/bitbake/lib/bb/server/process.py
index 43790b6..5d02c0b 100644
--- a/poky/bitbake/lib/bb/server/process.py
+++ b/poky/bitbake/lib/bb/server/process.py
@@ -756,8 +756,11 @@
                 process.queue_signals = True
                 self._send(obj)
                 process.queue_signals = False
-                for sig in process.signal_received.pop():
-                    process.handle_sig(sig, None)
+                try:
+                    for sig in process.signal_received.pop():
+                        process.handle_sig(sig, None)
+                except IndexError:
+                    pass
         else:
             self._send(obj)
 
diff --git a/poky/bitbake/lib/bb/tests/fetch.py b/poky/bitbake/lib/bb/tests/fetch.py
index 622c46a..7fcf57e 100644
--- a/poky/bitbake/lib/bb/tests/fetch.py
+++ b/poky/bitbake/lib/bb/tests/fetch.py
@@ -468,6 +468,7 @@
                 "http://.*/.* file:///someotherpath/downloads/"
 
     def test_urireplace(self):
+        self.d.setVar("FILESPATH", ".")
         for k, v in self.replaceuris.items():
             ud = bb.fetch.FetchData(k[0], self.d)
             ud.setup_localpath(self.d)
@@ -693,6 +694,11 @@
         flst.sort()
         return flst
 
+    def test_local_checksum_fails_no_file(self):
+        self.d.setVar("SRC_URI", "file://404")
+        with self.assertRaises(bb.BBHandledException):
+            bb.fetch.get_checksum_file_list(self.d)
+
     def test_local(self):
         tree = self.fetchUnpack(['file://a', 'file://dir/c'])
         self.assertEqual(tree, ['a', 'dir/c'])
@@ -920,6 +926,7 @@
 
     @skipIfNoNetwork()
     def test_fetch_file_mirror_of_mirror(self):
+        self.d.setVar("FILESPATH", ".")
         self.d.setVar("MIRRORS", "http://.*/.* file:///some1where/ file:///some1where/.* file://some2where/ file://some2where/.* https://downloads.yoctoproject.org/releases/bitbake")
         fetcher = bb.fetch.Fetch(["http://invalid.yoctoproject.org/releases/bitbake/bitbake-1.0.tar.gz"], self.d)
         os.mkdir(self.dldir + "/some2where")
@@ -2895,3 +2902,28 @@
         fetcher = bb.fetch.Fetch([self.recipe_url], self.d)
         with self.assertRaises(bb.fetch2.NetworkAccess):
             fetcher.download()
+
+class FetchPremirroronlyBrokenTarball(FetcherTest):
+
+    def setUp(self):
+        super(FetchPremirroronlyBrokenTarball, self).setUp()
+        self.mirrordir = os.path.join(self.tempdir, "mirrors")
+        os.mkdir(self.mirrordir)
+        self.reponame = "bitbake"
+        self.gitdir = os.path.join(self.tempdir, "git", self.reponame)
+        self.recipe_url = "git://git.fake.repo/bitbake"
+        self.d.setVar("BB_FETCH_PREMIRRORONLY", "1")
+        self.d.setVar("BB_NO_NETWORK", "1")
+        self.d.setVar("PREMIRRORS", self.recipe_url + " " + "file://{}".format(self.mirrordir) + " \n")
+        self.mirrorname = "git2_git.fake.repo.bitbake.tar.gz"
+        with open(os.path.join(self.mirrordir, self.mirrorname), 'w') as targz:
+            targz.write("This is not tar.gz file!")
+
+    def test_mirror_broken_download(self):
+        import sys
+        self.d.setVar("SRCREV", "0"*40)
+        fetcher = bb.fetch.Fetch([self.recipe_url], self.d)
+        with self.assertRaises(bb.fetch2.FetchError):
+            fetcher.download()
+        stdout = sys.stdout.getvalue()
+        self.assertFalse(" not a git repository (or any parent up to mount point /)" in stdout)
diff --git a/poky/bitbake/lib/bb/tests/parse.py b/poky/bitbake/lib/bb/tests/parse.py
index 2898f9b..1a3b749 100644
--- a/poky/bitbake/lib/bb/tests/parse.py
+++ b/poky/bitbake/lib/bb/tests/parse.py
@@ -194,3 +194,26 @@
         self.assertTrue('addtask ignored: " do_patch"' in stdout)
         #self.assertTrue('dependent task do_foo for do_patch does not exist' in stdout)
 
+    broken_multiline_comment = """
+# First line of comment \\
+# Second line of comment \\
+
+"""
+    def test_parse_broken_multiline_comment(self):
+        f = self.parsehelper(self.broken_multiline_comment)
+        with self.assertRaises(bb.BBHandledException):
+            d = bb.parse.handle(f.name, self.d)['']
+
+
+    comment_in_var = """
+VAR = " \\
+    SOMEVAL \\
+#   some comment \\
+    SOMEOTHERVAL \\
+"
+"""
+    def test_parse_comment_in_var(self):
+        f = self.parsehelper(self.comment_in_var)
+        with self.assertRaises(bb.BBHandledException):
+            d = bb.parse.handle(f.name, self.d)['']
+