diff --git a/demos/wscript b/demos/wscript
index 90578f00..96036c07 100644
--- a/demos/wscript
+++ b/demos/wscript
@@ -87,7 +87,7 @@ def configure(conf):
 			conf.find_program('python'+x, var=x)
 			# unpacking the waf directory concurrently can lead to a race condition, we'll need to take care of this (thanks, build farm!)
 			conf.cmd_and_log(conf.env[x] + ['./waf', '--version'], env={})
-		except Exception as e:
+		except Errors.WafError as e:
 			pass
 		else:
 			conf.env.append_value('PYTHONS', x)
diff --git a/playground/dynamic_build3/wscript b/playground/dynamic_build3/wscript
index 1c3f1c73..6864ea9a 100644
--- a/playground/dynamic_build3/wscript
+++ b/playground/dynamic_build3/wscript
@@ -11,8 +11,8 @@ An advanced dynamic build simulating a call to an external system.
 That external build system produces a library which is then used in the current build.
 """
 
-import os, shutil, sys, subprocess
-from waflib import Utils, Build, Logs
+import os, shutil, sys
+from waflib import Build, Errors, Logs
 
 top = '.'
 out = 'build'
@@ -79,7 +79,7 @@ def some_fun(task):
 
 	try:
 		task.generator.bld.cmd_and_log(cmd, cwd=cwd, quiet=0, output=0)
-	except Exception as e:
+	except Errors.WafError as e:
 		try:
 			print(e.stderr)
 		except AttributeError:
diff --git a/waflib/Configure.py b/waflib/Configure.py
index 0a1ff57f..6f86fd3a 100644
--- a/waflib/Configure.py
+++ b/waflib/Configure.py
@@ -428,6 +428,7 @@ def find_program(self, filename, **kw):
 	:type msg: string
 	:param interpreter: interpreter for the program
 	:type interpreter: ConfigSet variable key
+	:raises: :py:class:`waflib.Errors.ConfigurationError`
 	"""
 
 	exts = kw.get('exts', Utils.is_win32 and '.exe,.com,.bat,.cmd' or ',.sh,.pl,.py')
diff --git a/waflib/Context.py b/waflib/Context.py
index 249a9dac..f286bbae 100644
--- a/waflib/Context.py
+++ b/waflib/Context.py
@@ -323,6 +323,8 @@ class Context(ctx):
 		:type kw: dict
 		:returns: process exit status
 		:rtype: integer
+		:raises: :py:class:`waflib.Errors.WafError` if an invalid executable is specified for a non-shell process
+		:raises: :py:class:`waflib.Errors.WafError` in case of execution failure
 		"""
 		subprocess = Utils.subprocess
 		kw['shell'] = isinstance(cmd, str)
@@ -382,7 +384,7 @@ class Context(ctx):
 		"""
 		Executes a process and returns stdout/stderr if the execution is successful.
 		An exception is thrown when the exit status is non-0. In that case, both stderr and stdout
-		will be bound to the WafError object::
+		will be bound to the WafError object (configuration tests)::
 
 			def configure(conf):
 				out = conf.cmd_and_log(['echo', 'hello'], output=waflib.Context.STDOUT, quiet=waflib.Context.BOTH)
@@ -390,7 +392,7 @@ class Context(ctx):
 				(out, err) = conf.cmd_and_log(cmd, input='\\n'.encode(), output=waflib.Context.STDOUT)
 				try:
 					conf.cmd_and_log(['which', 'someapp'], output=waflib.Context.BOTH)
-				except Exception as e:
+				except Errors.WafError as e:
 					print(e.stdout, e.stderr)
 
 		:param cmd: args for subprocess.Popen
diff --git a/waflib/Tools/c_config.py b/waflib/Tools/c_config.py
index 6a11d1d5..1a865614 100644
--- a/waflib/Tools/c_config.py
+++ b/waflib/Tools/c_config.py
@@ -1024,7 +1024,7 @@ def get_cc_version(conf, cc, gcc=False, icc=False, clang=False):
 	env = conf.env.env or None
 	try:
 		out, err = conf.cmd_and_log(cmd, output=0, input='\n'.encode(), env=env)
-	except Exception:
+	except Errors.WafError:
 		conf.fatal('Could not determine the compiler version %r' % cmd)
 
 	if gcc:
diff --git a/waflib/Tools/irixcc.py b/waflib/Tools/irixcc.py
index 706ec496..c3ae1ac9 100644
--- a/waflib/Tools/irixcc.py
+++ b/waflib/Tools/irixcc.py
@@ -6,6 +6,7 @@
 Compiler definition for irix/MIPSpro cc compiler
 """
 
+from waflib import Errors
 from waflib.Tools import ccroot, ar
 from waflib.Configure import conf
 
@@ -24,7 +25,7 @@ def find_irixcc(conf):
 
 	try:
 		conf.cmd_and_log(cc + ['-version'])
-	except Exception:
+	except Errors.WafError:
 		conf.fatal('%r -version could not be executed' % cc)
 
 	v.CC = cc
diff --git a/waflib/Tools/perl.py b/waflib/Tools/perl.py
index 90e47ea8..05bbd9df 100644
--- a/waflib/Tools/perl.py
+++ b/waflib/Tools/perl.py
@@ -24,7 +24,7 @@ Support for Perl extensions. A C/C++ compiler is required::
 """
 
 import os
-from waflib import Task, Options, Utils
+from waflib import Task, Options, Utils, Errors
 from waflib.Configure import conf
 from waflib.TaskGen import extension, feature, before_method
 
@@ -99,7 +99,7 @@ def check_perl_module(self, module):
 	self.start_msg('perl module %s' % module)
 	try:
 		r = self.cmd_and_log(cmd)
-	except Exception:
+	except Errors.WafError:
 		self.end_msg(False)
 		return None
 	self.end_msg(r or True)
diff --git a/waflib/Tools/python.py b/waflib/Tools/python.py
index a536f696..11b0318d 100644
--- a/waflib/Tools/python.py
+++ b/waflib/Tools/python.py
@@ -19,7 +19,7 @@ Support for Python, detect the headers and libraries and provide
 """
 
 import os, sys
-from waflib import Utils, Options, Errors, Logs, Task, Node
+from waflib import Errors, Logs, Node, Options, Task, Utils
 from waflib.TaskGen import extension, before_method, after_method, feature
 from waflib.Configure import conf
 
@@ -553,7 +553,7 @@ def check_python_module(conf, module_name, condition=''):
 	conf.start_msg(msg)
 	try:
 		ret = conf.cmd_and_log(conf.env.PYTHON + ['-c', PYTHON_MODULE_TEMPLATE % module_name])
-	except Exception:
+	except Errors.WafError:
 		conf.end_msg(False)
 		conf.fatal('Could not find the python module %r' % module_name)
 
diff --git a/waflib/Tools/ruby.py b/waflib/Tools/ruby.py
index d92f0270..eef37369 100644
--- a/waflib/Tools/ruby.py
+++ b/waflib/Tools/ruby.py
@@ -23,7 +23,7 @@ Support for Ruby extensions. A C/C++ compiler is required::
 """
 
 import os
-from waflib import Options, Utils, Task
+from waflib import Errors, Options, Task, Utils
 from waflib.TaskGen import before_method, feature, extension
 from waflib.Configure import conf
 
@@ -60,13 +60,13 @@ def check_ruby_version(self, minver=()):
 
 	try:
 		version = self.cmd_and_log(ruby + ['-e', 'puts defined?(VERSION) ? VERSION : RUBY_VERSION']).strip()
-	except Exception:
+	except Errors.WafError:
 		self.fatal('could not determine ruby version')
 	self.env.RUBY_VERSION = version
 
 	try:
-		ver = tuple(map(int, version.split(".")))
-	except Exception:
+		ver = tuple(map(int, version.split('.')))
+	except Errors.WafError:
 		self.fatal('unsupported ruby version %r' % version)
 
 	cver = ''
@@ -151,7 +151,7 @@ def check_ruby_module(self, module_name):
 	self.start_msg('Ruby module %s' % module_name)
 	try:
 		self.cmd_and_log(self.env.RUBY + ['-e', 'require \'%s\';puts 1' % module_name])
-	except Exception:
+	except Errors.WafError:
 		self.end_msg(False)
 		self.fatal('Could not find the ruby module %r' % module_name)
 	self.end_msg(True)
diff --git a/waflib/Tools/suncc.py b/waflib/Tools/suncc.py
index 39481e31..602e6392 100644
--- a/waflib/Tools/suncc.py
+++ b/waflib/Tools/suncc.py
@@ -3,6 +3,7 @@
 # Thomas Nagy, 2006-2017 (ita)
 # Ralf Habacker, 2006 (rh)
 
+from waflib import Errors
 from waflib.Tools import ccroot, ar
 from waflib.Configure import conf
 
@@ -15,7 +16,7 @@ def find_scc(conf):
 	cc = conf.find_program('cc', var='CC')
 	try:
 		conf.cmd_and_log(cc + ['-flags'])
-	except Exception:
+	except Errors.WafError:
 		conf.fatal('%r is not a Sun compiler' % cc)
 	v.CC_NAME = 'sun'
 	conf.get_suncc_version(cc)
diff --git a/waflib/Tools/suncxx.py b/waflib/Tools/suncxx.py
index 97ce060b..a5921277 100644
--- a/waflib/Tools/suncxx.py
+++ b/waflib/Tools/suncxx.py
@@ -3,6 +3,7 @@
 # Thomas Nagy, 2006-2017 (ita)
 # Ralf Habacker, 2006 (rh)
 
+from waflib import Errors
 from waflib.Tools import ccroot, ar
 from waflib.Configure import conf
 
@@ -15,7 +16,7 @@ def find_sxx(conf):
 	cc = conf.find_program(['CC', 'c++'], var='CXX')
 	try:
 		conf.cmd_and_log(cc + ['-flags'])
-	except Exception:
+	except Errors.WafError:
 		conf.fatal('%r is not a Sun compiler' % cc)
 	v.CXX_NAME = 'sun'
 	conf.get_suncc_version(cc)
diff --git a/waflib/Tools/vala.py b/waflib/Tools/vala.py
index 266c0132..df90a7d3 100644
--- a/waflib/Tools/vala.py
+++ b/waflib/Tools/vala.py
@@ -9,7 +9,7 @@ this tool to be too stable either (apis, etc)
 """
 
 import re
-from waflib import Build, Context, Task, Utils, Logs, Options, Errors, Node
+from waflib import Build, Context, Errors, Logs, Node, Options, Task, Utils
 from waflib.TaskGen import extension, taskgen_method
 from waflib.Configure import conf
 
@@ -274,7 +274,7 @@ def find_valac(self, valac_name, min_version):
 	valac = self.find_program(valac_name, var='VALAC')
 	try:
 		output = self.cmd_and_log(valac + ['--version'])
-	except Exception:
+	except Errors.WafError:
 		valac_version = None
 	else:
 		ver = re.search(r'\d+.\d+.\d+', output).group().split('.')
diff --git a/waflib/extras/pgicc.py b/waflib/extras/pgicc.py
index d06e7f1a..9790b9cf 100644
--- a/waflib/extras/pgicc.py
+++ b/waflib/extras/pgicc.py
@@ -7,6 +7,7 @@ Detect the PGI C compiler
 """
 
 import sys, re
+from waflib import Errors
 from waflib.Configure import conf
 from waflib.Tools.compiler_c import c_compiler
 c_compiler['linux'].append('pgicc')
@@ -42,7 +43,7 @@ def get_pgi_version(conf, cc):
 
 	try:
 		out, err = conf.cmd_and_log(cmd, output=0)
-	except Exception:
+	except Errors.WafError:
 		conf.fatal('Could not find pgi compiler %r' % cmd)
 
 	if out:
@@ -56,7 +57,7 @@ def get_pgi_version(conf, cc):
 	cmd = cc + ['-help=variable']
 	try:
 		out, err = conf.cmd_and_log(cmd, output=0)
-	except Exception:
+	except Errors.WafError:
 		conf.fatal('Could not find pgi compiler %r' % cmd)
 
 	version = re.findall('^COMPVER\s*=(.*)', out, re.M)
diff --git a/wscript b/wscript
index 10960200..5080f5a6 100644
--- a/wscript
+++ b/wscript
@@ -23,7 +23,7 @@ PRELUDE = ''
 import os, sys, re, io, optparse, tokenize
 from hashlib import md5
 
-from waflib import Utils, Options, Logs, Scripting
+from waflib import Errors, Utils, Options, Logs, Scripting
 from waflib import Configure
 Configure.autoconfig = 1
 
@@ -64,9 +64,10 @@ def init(ctx):
 
 		try:
 			rev = ctx.cmd_and_log("git rev-parse HEAD").strip()
-			pats.append(('^WAFREVISION(.*)', 'WAFREVISION="%s"' % rev))
-		except Exception:
+		except Errors.WafError:
 			rev = ''
+		else:
+			pats.append(('^WAFREVISION(.*)', 'WAFREVISION="%s"' % rev))
 
 		sub_file('waflib/Context.py', pats)
 
@@ -344,7 +345,7 @@ def create_waf(self, *k, **kw):
 	bld = self.generator.bld
 	try:
 		rev = bld.cmd_and_log('git rev-parse HEAD', quiet=0).strip()
-	except Exception:
+	except Errors.WafError:
 		rev = ''
 	else:
 		reg = re.compile('^GIT(.*)', re.M)