Index: generic/tclIOCmd.c
==================================================================
--- generic/tclIOCmd.c
+++ generic/tclIOCmd.c
@@ -385,11 +385,12 @@
     Tcl_Channel chan;		/* The channel to read from. */
     int newline, i;		/* Discard newline at end? */
     int toRead;			/* How many bytes to read? */
     int charactersRead;		/* How many characters were read? */
     int mode;			/* Mode in which channel is opened. */
-    Tcl_Obj *resultPtr, *resultDictPtr, *returnOptsPtr, *chanObjPtr;
+    int exitstatus = TCL_OK;
+    Tcl_Obj *resultPtr, *chanObjPtr;
 
     if ((objc != 2) && (objc != 3)) {
 	Interp *iPtr;
 
     argerror:
@@ -469,32 +470,24 @@
 	 * Capture error messages put by the driver into the bypass area and
 	 * put them into the regular interpreter result. Fall back to the
 	 * regular message if nothing was found in the bypass.
 	 */
 
-	if (!TclChanCaughtErrorBypass(interp, chan)) {
-	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
-		    "error reading \"%s\": %s",
-		    TclGetString(chanObjPtr), Tcl_PosixError(interp)));
-	}
-	resultDictPtr = Tcl_NewDictObj();
-	Tcl_DictObjPut(NULL, resultDictPtr, Tcl_NewStringObj("read", -1)
-	    , resultPtr);
-	returnOptsPtr = Tcl_NewDictObj();
-	Tcl_DictObjPut(NULL, returnOptsPtr, Tcl_NewStringObj("-result", -1)
-	    , resultDictPtr);
-	TclChannelRelease(chan);
-	Tcl_DecrRefCount(resultPtr);
-	Tcl_SetReturnOptions(interp, returnOptsPtr);
-	return TCL_ERROR;
-    }
-
-    /*
-     * If requested, remove the last newline in the channel if at EOF.
-     */
-
-    if ((charactersRead > 0) && (newline != 0)) {
+	if (TclChanCaughtErrorBypass(interp, chan)) {
+	    Tcl_AddObjErrorInfo(interp, Tcl_GetString(Tcl_ObjPrintf(
+		"\n %s", Tcl_GetString(Tcl_GetObjResult(interp)))),-1);
+	} else {
+	    Tcl_AddObjErrorInfo(interp, Tcl_GetString(Tcl_ObjPrintf(
+		"error reading \"%s\": %s",
+		TclGetString(chanObjPtr), Tcl_PosixError(interp))), -1);
+	}
+	exitstatus = TCL_ERROR;
+    } else if ((charactersRead > 0) && (newline != 0)) {
+	/*
+	 * If requested, remove the last newline in the channel if at EOF.
+	 */
+
 	const char *result;
 	int length;
 
 	result = TclGetStringFromObj(resultPtr, &length);
 	if (result[length - 1] == '\n') {
@@ -502,11 +495,11 @@
 	}
     }
     Tcl_SetObjResult(interp, resultPtr);
     TclChannelRelease(chan);
     Tcl_DecrRefCount(resultPtr);
-    return TCL_OK;
+    return exitstatus;
 }
 
 /*
  *----------------------------------------------------------------------
  *

Index: tests/io.test
==================================================================
--- tests/io.test
+++ tests/io.test
@@ -1548,41 +1548,41 @@
     scan [string index $in end] %c
 } 160
 
 
 apply [list {} {
-	set template {
-		test io-12.9.@variant@ {ReadChars: multibyte chars split, default (strict)} -body {
-			set res {}
-			set f [open $path(test1) w]
-			fconfigure $f -translation binary
-			puts -nonewline $f [string repeat a 9]\xC2
-			close $f
-			set f [open $path(test1)]
-			fconfigure $f -encoding utf-8 @strict@ -buffersize 10
-			set status [catch {read $f} cres copts]
-			set in [dict get $copts -result]
-			lappend res $in
-			lappend res $status $cres
-			set status [catch {read $f} cres copts]
-			set in [dict get $copts -result]
-			lappend res $in
-			lappend res $status $cres
-			set res
-		} -cleanup {
-			catch {close $f}
-		} -match glob -result {{read aaaaaaaaa} 1\
-			{error reading "*": illegal byte sequence}\
-			{read {}} 1 {error reading "*": illegal byte sequence}}
-	}
-
-	# strict encoding may be the default in Tcl 9, but in 8 it is not
-	foreach variant {encodingstrict} strict {{-strictencoding 1}} {
-		set script [string map [
-			list @variant@ $variant @strict@ $strict] $template] 
-		uplevel 1 $script
-	}
+    set template {
+	test io-12.9.@variant@ {ReadChars: multibyte chars split, default (strict)} -body {
+	    set res {}
+	    set f [open $path(test1) w]
+	    fconfigure $f -translation binary
+	    puts -nonewline $f [string repeat a 9]\xC2
+	    close $f
+	    set f [open $path(test1)]
+	    fconfigure $f -encoding utf-8 @strict@ -buffersize 10
+	    set status [catch {read $f} cres copts]
+	    set in [dict get $copts -errorinfo]
+	    lappend res $status $cres
+	    lappend res $in
+	    set status [catch {read $f} cres copts]
+	    set in [dict get $copts -errorinfo]
+	    lappend res $status $cres
+	    lappend res $in
+	    set res
+	} -cleanup {
+	    catch {close $f}
+	} -match glob -result {1 aaaaaaaaa\
+	    {error reading "*"*:*illegal byte sequence*"read $f"}\
+	    1 {} {error reading "*"*:*illegal byte sequence*"read $f"}}
+    }
+
+    # strict encoding may be the default in Tcl 9, but in 8 it is not
+    foreach variant {encodingstrict} strict {{-strictencoding 1}} {
+	set script [string map [
+	    list @variant@ $variant @strict@ $strict] $template] 
+	uplevel 1 $script
+    }
 } [namespace current]]
 
 
 test io-12.10 {ReadChars: multibyte chars split} -body {
     set f [open $path(test1) w]
@@ -9078,18 +9078,17 @@
     puts -nonewline $f A\x81
     flush $f
     seek $f 0
     fconfigure $f -encoding utf-8 -buffering none -eofchar "" -translation lf -strictencoding 1
 } -body {
-    set status [catch {read $f} cres copts]
-    set d [dict get $copts -result read]
+    set status [catch {read $f} d copts]
     binary scan $d H* hd
-    lappend hd $status $cres
+    lappend hd $status [dict get $copts -errorinfo]
 } -cleanup {
     close $f
     removeFile io-75.6
-} -match glob -result {41 1 {error reading "*": illegal byte sequence}}
+} -match glob -result {41 1 {error reading "*": illegal byte sequence*}}
 
 test io-75.7 {invalid utf-8 encoding eof handling (-strictencoding 1)} -setup {
     set fn [makeFile {} io-75.7]
     set f [open $fn w+]
     fconfigure $f -encoding binary
@@ -9097,23 +9096,22 @@
     puts -nonewline $f A\xA1\x1A
     flush $f
     seek $f 0
     fconfigure $f -encoding utf-8 -buffering none -eofchar \x1A -translation lf -strictencoding 1
 } -body {
-    set status [catch {read $f} cres copts]
-    set d [dict get $copts -result read]
+    set status [catch {read $f} d copts]
     binary scan $d H* hd
     lappend hd [eof $f]
     lappend hd $status
-    lappend hd $cres
+    lappend hd [dict get $copts -errorinfo]
     fconfigure $f -encoding iso8859-1
     lappend hd [read $f];# We changed encoding, so now we can read the \xA1
     close $f
     set hd
 } -cleanup {
     removeFile io-75.7
-} -match glob -result {41 0 1 {error reading "*": illegal byte sequence} ¡}
+} -match glob -result {41 0 1 {error reading "*": illegal byte sequence*} ¡}
 
 test io-75.8.incomplete {
     incomplete uft-8 char after eof char is not an error (-strictencoding 1)
 } -setup {
     set hd {}
@@ -9196,33 +9194,32 @@
 } -cleanup {
     removeFile io-75.10
 } -result 41c0
 
 
-test io-75.10_strict {incomplete multibyte encoding read is an error} -setup {
+test io-75.10.strict {incomplete multibyte encoding read is an error} -setup {
 	set res {}
     set fn [makeFile {} io-75.10]
     set f [open $fn w+]
     fconfigure $f -encoding binary
     puts -nonewline $f A\xC0
     flush $f
     seek $f 0
     fconfigure $f -encoding utf-8 -strictencoding 1 -buffering none
 } -body {
-    set status [catch {read $f} cres copts]
-    set d [dict get $copts -result read]
-    binary scan $d H* hd
-	lappend res $hd $cres
-	chan configure $f -encoding iso8859-1
-	set d [read $f]
-    binary scan $d H* hd
-	lappend res $hd
-    close $f
-	return $res
+    set status [catch {read $f} d copts]
+    binary scan $d H* hd
+    lappend res $hd [dict get $copts -errorinfo] 
+    chan configure $f -encoding iso8859-1
+    set d [read $f]
+    binary scan $d H* hd
+    lappend res $hd
+    close $f
+    return $res
 } -cleanup {
     removeFile io-75.10
-} -match glob -result {41 {error reading "*": illegal byte sequence} c0}
+} -match glob -result {41 {error reading "*": illegal byte sequence*} c0}
 
 
 # As utf-8 has a special treatment in multi-byte decoding, also test another
 # one.
 test io-75.11 {shiftjis encoding error read results in raw bytes} -setup {
@@ -9235,19 +9232,18 @@
     flush $f
     seek $f 0
     fconfigure $f -encoding shiftjis -buffering none -eofchar "" \
 		-translation lf -strictencoding 1
 } -body {
-    set status [catch {read $f} cres copts]
-    set d [dict get $copts -result read]
+    set status [catch {read $f} d copts]
     binary scan $d H* hd
     lappend hd $status
-    lappend hd $cres
+    lappend hd [dict get $copts -errorinfo]
 } -cleanup {
     close $f
     removeFile io-75.11
-} -match glob -result {41 1 {error reading "*": illegal byte sequence}}
+} -match glob -result {41 1 {error reading "*": illegal byte sequence*}}
 
 
 test io-75.12 {invalid utf-8 encoding read is an error} -setup {
 	set res {}
     set fn [makeFile {} io-75.12]
@@ -9257,20 +9253,19 @@
     flush $f
     seek $f 0
     fconfigure $f -encoding utf-8 -buffering none -eofchar {} -translation lf \
 		-strictencoding 1
 } -body {
-    set status [catch {read $f} cres copts]
-    set d [dict get $copts -result read]
+    set status [catch {read $f} d copts]
     close $f
     binary scan $d H* hd
-	lappend res $hd $status $cres
-	return $res
+    lappend res $hd $status [dict get $copts -errorinfo]
+    return $res
 } -cleanup {
     removeFile io-75.12
-} -match glob -result {41 1 {error reading "*": illegal byte sequence}}
-test io-75.12_ignore {invalid utf-8 encoding read is ignored} -setup {
+} -match glob -result {41 1 {error reading "*": illegal byte sequence*}}
+test io-75.12.ignore {invalid utf-8 encoding read is ignored} -setup {
     set fn [makeFile {} io-75.12]
     set f [open $fn w+]
     fconfigure $f -encoding binary
     puts -nonewline $f A\x81
     flush $f
@@ -9293,19 +9288,18 @@
     puts -nonewline $f "A\x81"
     flush $f
     seek $f 0
     fconfigure $f -encoding utf-8 -buffering none -eofchar "" -translation lf -strictencoding 1
 } -body {
-    set status [catch {read $f} cres copts]
-    set d [dict get $copts -result read]
+    set status [catch {read $f} d copts]
     binary scan $d H* hd
     lappend hd $status
     close $f
-    lappend hd $cres
+    lappend hd [dict get $copts -errorinfo]
 } -cleanup {
     removeFile io-75.13
-} -match glob -result {41 1 {error reading "*": illegal byte sequence}}
+} -match glob -result {41 1 {error reading "*": illegal byte sequence*}}
 
 test io-75.14 {invalid utf-8 encoding [gets] coninues in non-strict mode after error} -setup {
     set res {} 
     set fn [makeFile {} io-75.14]
     set f [open $fn w+]

Index: tests/ioCmd.test
==================================================================
--- tests/ioCmd.test
+++ tests/ioCmd.test
@@ -862,12 +862,15 @@
 	    return a
 	}
     }
     set ch [chan create read foo]
 } -body {
-    read $ch 1
-} -returnCodes error -cleanup {
+    set status [catch {
+	read $ch 1
+    } cres copts]
+    list $status [dict get $copts -errorinfo]
+} -cleanup {
     catch {close $ch}
     rename foo {}
 } -match glob -result {*invalid argument*}
 test iocmd-21.23 {[close] in [gets] segfaults} -setup {
     proc foo {method chan args} {
@@ -1056,20 +1059,22 @@
     rename foo {}
     set res
 } -result {{read rc* 4096} {read rc* 4096} snarfsnarf}
 test iocmd-23.2 {chan read, bad data return, to much} -match glob -body {
     set res {}
-    proc foo {args} {
+    proc foo args {
 	oninit; onfinal; track
 	return [string repeat snarf 1000]
     }
     set c [chan create {r w} foo]
-    note [catch {read $c 2} msg]; note $msg
+    note [catch {read $c 2} msg copts]
+    note $msg
+    note [dict get $copts -errorinfo]
     close $c
     rename foo {}
     set res
-} -result {{read rc* 4096} 1 {read delivered more than requested}}
+} -result {{read rc* 4096} 1 {} {read delivered more than requested*}}
 test iocmd-23.3 {chan read, for non-readable channel} -match glob -body {
     set res {}
     proc foo {args} {
 	oninit; onfinal; track; note MUST_NOT_HAPPEN
     }
@@ -1084,63 +1089,74 @@
     proc foo {args} {
 	oninit; onfinal; track
 	return -code error BOOM!
     }
     set c [chan create {r w} foo]
-    note [catch {read $c 2} msg]; note $msg
+    note [catch {read $c 2} msg copts]
+    note $msg
+    note [dict get $copts -errorinfo]
     close $c
     rename foo {}
     set res
-} -result {{read rc* 4096} 1 BOOM!}
+} -result {{read rc* 4096} 1 {} {BOOM!*}}
 test iocmd-23.5 {chan read, break return is error} -match glob -body {
     set res {}
     proc foo {args} {
 	oninit; onfinal; track
 	return -code break BOOM!
     }
     set c [chan create {r w} foo]
-    note [catch {read $c 2} msg]; note $msg
+    note [catch {read $c 2} msg copts]
+    note $msg
+    note [dict get $copts -errorinfo]
     close $c
     rename foo {}
     set res
-} -result {{read rc* 4096} 1 *bad code*}
+} -result {{read rc* 4096} 1 {} {chan handler *bad code*}}
 test iocmd-23.6 {chan read, continue return is error} -match glob -body {
     set res {}
     proc foo {args} {
 	oninit; onfinal; track
 	return -code continue BOOM!
     }
     set c [chan create {r w} foo]
-    note [catch {read $c 2} msg]; note $msg
+    note [catch {read $c 2} msg copts]
+    note $msg
+    note [dict get $copts -errorinfo]
     close $c
     rename foo {}
     set res
-} -result {{read rc* 4096} 1 *bad code*}
+} -result {{read rc* 4096} 1 {} {chan handler *bad code*}}
 test iocmd-23.7 {chan read, custom return is error} -match glob -body {
     set res {}
     proc foo {args} {
 	oninit; onfinal; track
 	return -code 777 BOOM!
     }
     set c [chan create {r w} foo]
-    note [catch {read $c 2} msg]; note $msg
+    note [catch {read $c 2} msg copts]
+    note $msg
+    note [dict get $copts -errorinfo]
     close $c
     rename foo {}
     set res
-} -result {{read rc* 4096} 1 *bad code*}
+} -result {{read rc* 4096} 1 {} {chan handler *bad code*}}
 test iocmd-23.8 {chan read, level is squashed} -match glob -body {
     set res {}
     proc foo {args} {
 	oninit; onfinal; track
 	return -level 55 -code 777 BOOM!
     }
     set c [chan create {r w} foo]
-    note [catch {read $c 2} msg opt]; note $msg; noteOpts $opt
+    note [catch {read $c 2} msg opt]
+    note $msg
+    noteOpts $opt
     close $c
     rename foo {}
     set res
-} -result {{read rc* 4096} 1 *bad code* {-code 1 -level 0 -errorcode NONE -errorline 1 -errorinfo *bad code*subcommand "read"*}}
+} -result {{read rc* 4096} 1 {} {-code 1 -level 0 -errorcode NONE\
+    -errorline 1 -errorinfo *bad code*subcommand "read"*}}
 test iocmd-23.9 {chan read, no data means eof} -match glob -setup {
     set res {}
     proc foo {args} {
 	oninit; onfinal; track
 	return ""

Index: tests/ioTrans.test
==================================================================
--- tests/ioTrans.test
+++ tests/ioTrans.test
@@ -448,16 +448,17 @@
 	handle.finalize
 	lappend ::res $args
 	return -code error BOOM!
     }
     set c [chan push [tempchan] foo]
-    lappend res [catch {read $c 2} msg] $msg
+    lappend res [catch {read $c 2} msg copts] $msg
+    lappend res [dict get $copts -errorinfo]
 } -cleanup {
     tempdone
     rename foo {}
 } -result {{read rt* {test data
-}} 1 BOOM!}
+}} 1 {} {BOOM!*}}
 test iortrans-4.4 {chan read, break return is error} -setup {
     set res {}
 } -match glob -body {
     proc foo {args} {
 	handle.initialize
@@ -464,16 +465,17 @@
 	handle.finalize
 	lappend ::res $args
 	return -code break BOOM!
     }
     set c [chan push [tempchan] foo]
-    lappend res [catch {read $c 2} msg] $msg
+    lappend res [catch {read $c 2} msg copts] $msg
+    lappend res [dict get $copts -errorinfo]
 } -cleanup {
     tempdone
     rename foo {}
 } -result {{read rt* {test data
-}} 1 *bad code*}
+}} 1 {} {chan handler returned bad code*}}
 test iortrans-4.5 {chan read, continue return is error} -setup {
     set res {}
 } -match glob -body {
     proc foo {args} {
 	handle.initialize
@@ -480,16 +482,17 @@
 	handle.finalize
 	lappend ::res $args
 	return -code continue BOOM!
     }
     set c [chan push [tempchan] foo]
-    lappend res [catch {read $c 2} msg] $msg
+    lappend res [catch {read $c 2} msg copts] $msg
+    lappend res [dict get $copts -errorinfo]
 } -cleanup {
     tempdone
     rename foo {}
 } -result {{read rt* {test data
-}} 1 *bad code*}
+}} 1 {} {chan handler returned bad code*}}
 test iortrans-4.6 {chan read, custom return is error} -setup {
     set res {}
 } -match glob -body {
     proc foo {args} {
 	handle.initialize
@@ -496,16 +499,17 @@
 	handle.finalize
 	lappend ::res $args
 	return -code 777 BOOM!
     }
     set c [chan push [tempchan] foo]
-    lappend res [catch {read $c 2} msg] $msg
+    lappend res [catch {read $c 2} msg copts] $msg
+    lappend res [dict get $copts -errorinfo]
 } -cleanup {
     tempdone
     rename foo {}
 } -result {{read rt* {test data
-}} 1 *bad code*}
+}} 1 {} {chan handler returned bad code*}}
 test iortrans-4.7 {chan read, level is squashed} -setup {
     set res {}
 } -match glob -body {
     proc foo {args} {
 	handle.initialize
@@ -518,11 +522,12 @@
     noteOpts $opt
 } -cleanup {
     tempdone
     rename foo {}
 } -result {{read rt* {test data
-}} 1 *bad code* {-code 1 -level 0 -errorcode NONE -errorline 1 -errorinfo *bad code*subcommand "read"*}}
+}} 1 {} {-code 1 -level 0 -errorcode NONE -errorline 1\
+    -errorinfo *bad code*subcommand "read"*}}
 test iortrans-4.8 {chan read, read, bug 2921116} -setup {
     set res {}
 } -match glob -body {
     proc foo {fd args} {
 	handle.initialize

Index: tests/zlib.test
==================================================================
--- tests/zlib.test
+++ tests/zlib.test
@@ -21,10 +21,11 @@
     # Work around a bug in some versions of zlib; known to manifest on at
     # least Mac OS X Mountain Lion...
     testConstraint recentZlib \
 	    [package vsatisfies [zlib::pkgconfig get zlibVersion] 1.2.6]
 }
+interp bgerror {} [list [namespace current]::bgerror]
 
 test zlib-1.1 {zlib basics} -constraints zlib -returnCodes error -body {
     zlib
 } -result {wrong # args: should be "zlib command arg ?...?"}
 test zlib-1.2 {zlib basics} -constraints zlib -returnCodes error -body {
@@ -699,11 +700,11 @@
 } -cleanup {
     unset -nocomplain total
     close $srv
 } -result {eof 500}
 test zlib-9.9 "bug #2818131 (gzip mismatch)" -constraints zlib -setup {
-    proc bgerror {s} {set ::total [list error $s]}
+    proc bgerror {s o} {set ::total [list error $s [dict get $o -errorinfo]]}
     set srv [socket -myaddr localhost -server {apply {{c a p} {
         chan configure $c -translation binary -buffering none -blocking 0
         zlib push gzip $c
         puts -nonewline $c [string repeat hello 100]
         close $c
@@ -730,13 +731,13 @@
     set ::total
 } -cleanup {
     unset -nocomplain total
     close $srv
     rename bgerror {}
-} -result {error {invalid block type}}
+} -match glob -result {error {} invalid\\ block\\ type*}
 test zlib-9.10 "bug #2818131 (compress mismatch)" -constraints zlib -setup {
-    proc bgerror {s} {set ::total [list error $s]}
+    proc bgerror {s o} {set ::total [list error $s [dict get $o -errorinfo]]}
     set srv [socket -myaddr localhost -server {apply {{c a p} {
         chan configure $c -translation binary -buffering none -blocking 0
         zlib push compress $c
         puts -nonewline $c [string repeat hello 100]
         close $c
@@ -763,13 +764,13 @@
     set ::total
 } -cleanup {
     unset -nocomplain total
     close $srv
     rename bgerror {}
-} -result {error {invalid stored block lengths}}
+} -match glob -result {error {} invalid\\ stored\\ block\\ lengths*}
 test zlib-9.11 "bug #2818131 (deflate mismatch)" -constraints zlib -setup {
-    proc bgerror {s} {set ::total [list error $s]}
+    proc bgerror {s o} {set ::total [list error $s [dict get $o -errorinfo]]}
     set srv [socket -myaddr localhost -server {apply {{c a p} {
         chan configure $c -translation binary -buffering none -blocking 0
         zlib push deflate $c
         puts -nonewline $c [string repeat hello 100]
         close $c
@@ -796,16 +797,16 @@
     set ::total
 } -cleanup {
     unset -nocomplain total
     close $srv
     rename bgerror {}
-} -result {error {incorrect header check}}
+} -match glob -result {error {} incorrect\\ header\\ check*}
 
 test zlib-10.0 "bug #2818131 (close with null interp)" -constraints {
     zlib
 } -setup {
-    proc bgerror {s} {set ::total [list error $s]}
+    proc bgerror {s o} {set ::total [list error $s]}
     set srv [socket -myaddr localhost -server {apply {{c a p} {
         chan configure $c -translation binary
         zlib push inflate $c
         chan event $c readable [list apply {{c} {
             set d [read $c]
@@ -842,11 +843,11 @@
 } -returnCodes error \
   -result {bad event name "xyzzy": must be readable or writable}
 test zlib-10.1 "bug #2818131 (mismatch read)" -constraints {
     zlib
 } -setup {
-    proc bgerror {s} {set ::total [list error $s]}
+    proc bgerror {s o} {set ::total [list error $s [dict get $o -errorinfo]]}
     proc zlibRead {c} {
         set d [read $c]
         if {[eof $c]} {
             chan event $c readable {}
             close $c
@@ -876,15 +877,15 @@
     set ::total
 } -cleanup {
     close $srv
     rename bgerror {}
     rename zlibRead {}
-} -result {error {invalid block type}}
+} -match glob -result {error {} {invalid block type*}}
 test zlib-10.2 "bug #2818131 (mismatch gets)" -constraints {
     zlib
 } -setup {
-    proc bgerror {s} {set ::total [list error $s]}
+    proc bgerror {s o} {set ::total [list error $s]}
     proc zlibRead {c} {
         if {[gets $c line] < 0} {
             close $c
             set ::total [list error -1]
         } elseif {[eof $c]} {