emacs runs on Mac with tramp . And I have a test project on a remote machine (dev-sever): /home/xxx/project/test_gdb/. It has a simple file: test.c. test.c is compiled by gcc with -O0 -g to test_bin. test.c: 1 int foo(int a, int b) { 2 int c = a + b; 3 return c; 4 } 5 6 int main(void) { 7 return foo(3, 4); 8 } Steps: 1. Open test.c on dev-server in emacs 2. run 'M-x gdb' gdb -i=mi test_bin and open gdb-many-window mode. 3. In *gud-test* buffer, run: break 7 4. Run: run and gdb stop at line 7 5. Step into line 7 But the cursor of source buffer will not move at all. And then emacs become irresponsive after running several step commands. I press Ctrl-G several times. Then it returns error: json-read-string: Bad string format: "doesn't start with `\"'!" Here is the backtrace for above error: Debugger entered--Lisp error: (json-string-format "doesn't start with `\"'!") signal(json-string-format ("doesn't start with `\"'!")) json-read-string() json-read-object() apply(json-read-object nil) json-read() gdb-json-read-buffer(nil nil) gdb-json-partial-output() gdb-thread-list-handler-custom() gdb-thread-list-handler() apply(gdb-thread-list-handler nil) (save-current-buffer (set-buffer #) (apply (quote gdb-thread-list-handler) args)) (with-current-buffer # (apply (quote gdb-thread-list-handler) args)) (lambda (&rest args) (with-current-buffer # (apply (quote gdb-thread-list-handler) args)))() gdb-handle-reply(27) gdb-done-or-error("27" done "threads=[{id=\"1\",target-id=\"process 25128\",name=\"test\",frame={level=\"0\",addr=\"0x00000000004004f4\",func=\"main\",args=[],file=\"test.c\",fullname=\"/home/xxx/projects/tests/test_gdb/test.c\",line=\"7\"},state=\"stopped\",core=\"24\"}],current-thread-id=\"1\"" t) gdb-done("27" "threads=[{id=\"1\",target-id=\"process 25128\",name=\"test\",frame={level=\"0\",addr=\"0x00000000004004f4\",func=\"main\",args=[],file=\"test.c\",fullname=\"/home/xxx/projects/tests/test_gdb/test.c\",line=\"7\"},state=\"stopped\",core=\"24\"}],current-thread-id=\"1\"" t) gdbmi-bnf-incomplete-record-result("27" (gdb-done . progressive)) #[0 "\302\300\301\242\"\207" ["27" ((gdb-done . progressive)) gdbmi-bnf-incomplete-record-result] 3]() gdbmi-bnf-result-and-async-record-impl() gdbmi-bnf-async-record() gdbmi-bnf-out-of-band-record() gdbmi-bnf-output() gud-gdbmi-marker-filter("27^done,threads=[{id=\"1\",target-id=\"process 25128\",name=\"test\",frame={level=\"0\",addr=\"0x00000000004004f4\",func=\"main\",args=[],file=\"test.c\",fullname=\"/home/xxx/projects/tests/test_gdb/test.c\",line=\"7\"},state=\"stopped\",core=\"24\"}],current-thread-id=\"1\"\n(gdb) \n28^done,BreakpointTable={nr_rows=\"1\",nr_cols=\"6\",hdr=[{width=\"7\",alignment=\"-1\",col_name=\"number\",colhdr=\"Num\"},{width=\"14\",alignment=\"-1\",col_name=\"type\",colhdr=\"Type\"},{width=\"4\",alignment=\"-1\",col_name=\"disp\",colhdr=\"Disp\"},{width=\"3\",alignment=\"-1\",col_name=\"enabled\",colhdr=\"Enb\"},{width=\"18\",alignment=\"-1\",col_name=\"addr\",colhdr=\"Address\"},{width=\"40\",alignment=\"2\",col_name=\"what\",colhdr=\"What\"}],body=[bkpt={number=\"1\",type=\"breakpoint\",disp=\"keep\",enabled=\"y\",addr=\"0x00000000004004f4\",func=\"main\",file=\"test.c\",fullname=\"/home/xxx/projects/tests/test_gdb/test.c\",line=\"7\",thread-groups=[\"i1\"],times=\"1\",original-location=\"/home/xxx/projects/tests/test_gdb/test.c:7\"}]}\n(gdb) \n29^done,locals=[]\n(gdb) \n30^done,stack=[frame={level=\"0\",addr=\"") apply(gud-gdbmi-marker-filter "27^done,threads=[{id=\"1\",target-id=\"process 25128\",name=\"test\",frame={level=\"0\",addr=\"0x00000000004004f4\",func=\"main\",args=[],file=\"test.c\",fullname=\"/home/xxx/projects/tests/test_gdb/test.c\",line=\"7\"},state=\"stopped\",core=\"24\"}],current-thread-id=\"1\"\n(gdb) \n28^done,BreakpointTable={nr_rows=\"1\",nr_cols=\"6\",hdr=[{width=\"7\",alignment=\"-1\",col_name=\"number\",colhdr=\"Num\"},{width=\"14\",alignment=\"-1\",col_name=\"type\",colhdr=\"Type\"},{width=\"4\",alignment=\"-1\",col_name=\"disp\",colhdr=\"Disp\"},{width=\"3\",alignment=\"-1\",col_name=\"enabled\",colhdr=\"Enb\"},{width=\"18\",alignment=\"-1\",col_name=\"addr\",colhdr=\"Address\"},{width=\"40\",alignment=\"2\",col_name=\"what\",colhdr=\"What\"}],body=[bkpt={number=\"1\",type=\"breakpoint\",disp=\"keep\",enabled=\"y\",addr=\"0x00000000004004f4\",func=\"main\",file=\"test.c\",fullname=\"/home/xxx/projects/tests/test_gdb/test.c\",line=\"7\",thread-groups=[\"i1\"],times=\"1\",original-location=\"/home/xxx/projects/tests/test_gdb/test.c:7\"}]}\n(gdb) \n29^done,locals=[]\n(gdb) \n30^done,stack=[frame={level=\"0\",addr=\"") gud-marker-filter("27^done,threads=[{id=\"1\",target-id=\"process 25128\",name=\"test\",frame={level=\"0\",addr=\"0x00000000004004f4\",func=\"main\",args=[],file=\"test.c\",fullname=\"/home/xxx/projects/tests/test_gdb/test.c\",line=\"7\"},state=\"stopped\",core=\"24\"}],current-thread-id=\"1\"\n(gdb) \n28^done,BreakpointTable={nr_rows=\"1\",nr_cols=\"6\",hdr=[{width=\"7\",alignment=\"-1\",col_name=\"number\",colhdr=\"Num\"},{width=\"14\",alignment=\"-1\",col_name=\"type\",colhdr=\"Type\"},{width=\"4\",alignment=\"-1\",col_name=\"disp\",colhdr=\"Disp\"},{width=\"3\",alignment=\"-1\",col_name=\"enabled\",colhdr=\"Enb\"},{width=\"18\",alignment=\"-1\",col_name=\"addr\",colhdr=\"Address\"},{width=\"40\",alignment=\"2\",col_name=\"what\",colhdr=\"What\"}],body=[bkpt={number=\"1\",type=\"breakpoint\",disp=\"keep\",enabled=\"y\",addr=\"0x00000000004004f4\",func=\"main\",file=\"test.c\",fullname=\"/home/xxx/projects/tests/test_gdb/test.c\",line=\"7\",thread-groups=[\"i1\"],times=\"1\",original-location=\"/home/xxx/projects/tests/test_gdb/test.c:7\"}]}\n(gdb) \n29^done,locals=[]\n(gdb) \n30^done,stack=[frame={level=\"0\",addr=\"") gud-filter(# "27^done,threads=[{id=\"1\",target-id=\"process 25128\",name=\"test\",frame={level=\"0\",addr=\"0x00000000004004f4\",func=\"main\",args=[],file=\"test.c\",fullname=\"/home/xxx/projects/tests/test_gdb/test.c\",line=\"7\"},state=\"stopped\",core=\"24\"}],current-thread-id=\"1\"\n(gdb) \n28^done,BreakpointTable={nr_rows=\"1\",nr_cols=\"6\",hdr=[{width=\"7\",alignment=\"-1\",col_name=\"number\",colhdr=\"Num\"},{width=\"14\",alignment=\"-1\",col_name=\"type\",colhdr=\"Type\"},{width=\"4\",alignment=\"-1\",col_name=\"disp\",colhdr=\"Disp\"},{width=\"3\",alignment=\"-1\",col_name=\"enabled\",colhdr=\"Enb\"},{width=\"18\",alignment=\"-1\",col_name=\"addr\",colhdr=\"Address\"},{width=\"40\",alignment=\"2\",col_name=\"what\",colhdr=\"What\"}],body=[bkpt={number=\"1\",type=\"breakpoint\",disp=\"keep\",enabled=\"y\",addr=\"0x00000000004004f4\",func=\"main\",file=\"test.c\",fullname=\"/home/xxx/projects/tests/test_gdb/test.c\",line=\"7\",thread-groups=[\"i1\"],times=\"1\",original-location=\"/home/xxx/projects/tests/test_gdb/test.c:7\"}]}\n(gdb) \n29^done,locals=[]\n(gdb) \n30^done,stack=[frame={level=\"0\",addr=\"") In GNU Emacs 26.0.50 (build 1, x86_64-apple-darwin13.4.0, NS appkit-1265.21 Version 10.9.5 (Build 13F1911)) of 2017-06-11 built on builder10-9.local Windowing system distributor 'Apple', version 10.3.1504 Recent messages: Warning: arch-dependent data dir ’/Users/build/workspace/Emacs-Multi-Build/label/mavericks/emacs-source/nextstep/Emacs.app/Contents/MacOS/libexec/’: No such file or directory For information about GNU Emacs and the GNU system, type C-h C-a. user-error: Beginning of history; no preceding item user-error: End of history; no default available Quit Configured using: 'configure --with-ns '--enable-locallisppath=/Library/Application Support/Emacs/${version}/site-lisp:/Library/Application Support/Emacs/site-lisp' --with-modules' Configured features: NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS MODULES Important settings: value of $LC_ALL: en_US.UTF-8 value of $LANG: en_US.UTF-8 locale-coding-system: utf-8-unix Major mode: Fundamental Minor modes in effect: tooltip-mode: t global-eldoc-mode: t electric-indent-mode: t mouse-wheel-mode: t tool-bar-mode: t menu-bar-mode: t file-name-shadow-mode: t global-font-lock-mode: t blink-cursor-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t buffer-read-only: t line-number-mode: t transient-mark-mode: t Load-path shadows: None found. Features: (shadow sort mail-extr emacsbug message subr-x puny seq byte-opt gv bytecomp byte-compile cconv cl-loaddefs cl-lib dired dired-loaddefs format-spec rfc822 mml easymenu mml-sec password-cache epa derived epg epg-config gnus-util rmail rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils thingatpt time-date tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type mwheel term/ns-win ns-win ucs-normalize mule-util term/common-win tool-bar dnd fontset image regexp-opt fringe tabulated-list replace newcomment text-mode elisp-mode lisp-mode prog-mode register page menu-bar rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock syntax facemenu font-core term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european ethiopic indian cyrillic chinese composite charscript charprop case-table epa-hook jka-cmpr-hook help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs button faces cus-face macroexp files text-properties overlay sha1 md5 base64 format env code-pages mule custom widget hashtable-print-readable backquote kqueue cocoa ns multi-tty make-network-process emacs) Memory information: ((conses 16 203699 7694) (symbols 48 19849 1) (miscs 40 71 164) (strings 32 18182 5316) (string-bytes 1 600826) (vectors 16 34880) (vector-slots 8 694435 4243) (floats 8 49 67) (intervals 56 194 0) (buffers 976 12))