Forward and Backward synchronizations failed when path contains non-ASCII characters

[unbadfish]

SumatraPDF version

• Version v3.7.17694 64-bit Pre-release

Describe the bug
When the file path contains non-ASCII characters (e.g., Chinese characters), both forward and backward synchronization fail.
Corrected: In backward case, a info message appears: “No synchronization info at this position”.

To Reproduce

1. Create a TeX file whose path includes non-ASCII characters, and compile it. See attachment below. (tested with VS Code + LaTeX Workshop)
2. Trigger forward sync from VS Code to SumatraPDF — the sync fails, and there are (always) no purple highlight appears.
3. Double-click on text in SumatraPDF to trigger backward sync — the sync (always) fails.
4. Corrected: In step 2, there are (always) no message window.
5. Corrected: In step 3, there are (always) a message window shows: “No synchronization info at this position”.

Expected behavior

1. Forward sync should navigate to the corresponding position in SumatraPDF, and highlight the focused place in purple.
2. Backward sync should open and jump to the relevant line in the source file (VS Code).

File that reproduces the problem

No.	Path	Synch?
1	basic\testENG	can
2	basic\testCN	can
3	Test1 space\testENG1	can
4	Test1 space\testCN1	can
5	Test2 中文\testENG2	CANNOT (NEITHER forward and backward)
6	Test2 中文\testCN2	CANNOT (NEITHER forward and backward)
7	add1\test中文	CANNOT (NEITHER forward and backward)

Content from the unzipped testCN1.synctex file:

SyncTeX Version:1
Input:1:d:/Projects/A2_LATEX_Projects/D2_InverseSearch_issue/Test1 space/./testCN1.tex
Input:2:d:/ENV/texlive/2026/texmf-dist/tex/latex/ctex/ctexart.cls
Input:3:d:/ENV/texlive/2026/texmf-dist/tex/latex/ctex/config/ctexbackend.cfg
...

Content from the unzipped testCN2.synctex file:

SyncTeX Version:1
Input:1:d:/Projects/A2_LATEX_Projects/D2_InverseSearch_issue/Test2 中文/./testCN2.tex
Input:2:d:/ENV/texlive/2026/texmf-dist/tex/latex/ctex/ctexart.cls
Input:3:d:/ENV/texlive/2026/texmf-dist/tex/latex/ctex/config/ctexbackend.cfg
...

Discussion

• Comparing No. 1 and No. 3: spaces in the path do not affect synchronization.
• Comparing No. 3, No.5 and No. 7: non-ASCII characters (in direction name OR in file name) in the path will cause synchronization to fail.
• Comparing testCN1.synctex and testCN2.synctex: /. s in .synctex file do not affect synchronization.

Directory structure

D:\Projects\A2_LATEX_Projects\D2_InverseSearch_issue\
├─add1
│      test中文.aux
│      test中文.fdb_latexmk
│      test中文.fls
│      test中文.log
│      test中文.pdf
│      test中文.synctex.gz
│      test中文.tex
│      test中文.xdv
│      
├─basic
│      testCN.aux
│      testCN.fdb_latexmk
│      testCN.fls
│      testCN.log
│      testCN.pdf
│      testCN.synctex.gz
│      testCN.tex
│      testCN.xdv
│      testENG.aux
│      testENG.fdb_latexmk
│      testENG.fls
│      testENG.log
│      testENG.pdf
│      testENG.synctex.gz
│      testENG.tex
│      testENG.xdv
│
├─Test1 space
│      testCN1.aux
│      testCN1.fdb_latexmk
│      testCN1.fls
│      testCN1.log
│      testCN1.pdf
│      testCN1.synctex.gz
│      testCN1.tex
│      testCN1.xdv
│      testENG1.aux
│      testENG1.fdb_latexmk
│      testENG1.fls
│      testENG1.log
│      testENG1.pdf
│      testENG1.synctex.gz
│      testENG1.tex
│      testENG1.xdv
│
└─Test2 中文
        testCN2.aux
        testCN2.fdb_latexmk
        testCN2.fls
        testCN2.log
        testCN2.pdf
        testCN2.synctex.gz
        testCN2.tex
        testCN2.xdv
        testENG2.aux
        testENG2.fdb_latexmk
        testENG2.fls
        testENG2.log
        testENG2.pdf
        testENG2.synctex.gz
        testENG2.tex
        testENG2.xdv

Screenshots
testENG1 (No3), forward:

testENG2 (No5), forward:

testENG2 (No5), backward:

Relative Code

• Forward:
  

  sumatrapdf/src/SearchAndDDE.cpp

  Lines 606 to 666 in ab3bd6f

  	// Show the result of a PDF forward-search synchronization (initiated by a DDE command)
  	void ShowForwardSearchResult(MainWindow* win, const char* fileName, int line, int /* col */, int ret, int page,
  	Vec<Rect>& rects) {
  	ReportIf(!win->AsFixed());
  	DisplayModel* dm = win->AsFixed();
  	win->fwdSearchMark.rects.Reset();
  	const PageInfo* pi = dm->GetPageInfo(page);
  	if ((ret == PDFSYNCERR_SUCCESS) && (rects.size() > 0) && (nullptr != pi)) {
  	// remember the position of the search result for drawing the rect later on
  	win->fwdSearchMark.rects = rects;
  	win->fwdSearchMark.page = page;
  	win->fwdSearchMark.show = true;
  	win->fwdSearchMark.hideStep = 0;
  	if (!gGlobalPrefs->forwardSearch.highlightPermanent) {
  	SetTimer(win->hwndCanvas, HIDE_FWDSRCHMARK_TIMER_ID, HIDE_FWDSRCHMARK_DELAY_IN_MS, nullptr);
  	}
  	// Scroll to show the overall highlighted zone
  	int pageNo = page;
  	Rect overallrc = rects.at(0);
  	for (size_t i = 1; i < rects.size(); i++) {
  	overallrc = overallrc.Union(rects.at(i));
  	}
  	TextSel res = {1, 1, &pageNo, &overallrc};
  	if (!dm->PageVisible(page)) {
  	win->ctrl->GoToPage(page, true);
  	}
  	if (!dm->ShowResultRectToScreen(&res)) {
  	ScheduleRepaint(win, 0);
  	}
  	if (IsIconic(win->hwndFrame)) {
  	ShowWindowAsync(win->hwndFrame, SW_RESTORE);
  	}
  	return;
  	}
  	TempStr buf = nullptr;
  	NotificationCreateArgs args{};
  	args.hwndParent = win->hwndCanvas;
  	if (ret == PDFSYNCERR_SYNCFILE_NOTFOUND) {
  	args.msg = _TRA("No synchronization file found");
  	} else if (ret == PDFSYNCERR_SYNCFILE_CANNOT_BE_OPENED) {
  	args.msg = _TRA("Synchronization file cannot be opened");
  	} else if (ret == PDFSYNCERR_INVALID_PAGE_NUMBER) {
  	buf = str::FormatTemp(_TRA("Page number %u inexistant"), page);
  	} else if (ret == PDFSYNCERR_NO_SYNC_AT_LOCATION) {
  	args.msg = _TRA("No synchronization info at this position");
  	} else if (ret == PDFSYNCERR_UNKNOWN_SOURCEFILE) {
  	buf = str::FormatTemp(_TRA("Unknown source file (%s)"), fileName);
  	} else if (ret == PDFSYNCERR_NORECORD_IN_SOURCEFILE) {
  	buf = str::FormatTemp(_TRA("Source file %s has no synchronization point"), fileName);
  	} else if (ret == PDFSYNCERR_NORECORD_FOR_THATLINE) {
  	buf = str::FormatTemp(_TRA("No result found around line %u in file %s"), line, fileName);
  	} else if (ret == PDFSYNCERR_NOSYNCPOINT_FOR_LINERECORD) {
  	buf = str::FormatTemp(_TRA("No result found around line %u in file %s"), line, fileName);
  	}
  	if (buf) {
  	args.msg = buf;
  	ShowNotification(args);
  	}
  	}

• Backward:
  

  sumatrapdf/src/SearchAndDDE.cpp

  Lines 509 to 604 in ab3bd6f

  	// returns true if inverse search was performed
  	bool OnInverseSearch(MainWindow* win, int x, int y) {
  	if (!CanAccessDisk() || gPluginMode) {
  	return false;
  	}
  	WindowTab* tab = win->CurrentTab();
  	if (!tab || tab->GetEngineType() != kindEngineMupdf) {
  	return false;
  	}
  	DisplayModel* dm = tab->AsFixed();
  	// Clear the last forward-search result
  	win->fwdSearchMark.rects.Reset();
  	InvalidateRect(win->hwndCanvas, nullptr, FALSE);
  	// On double-clicking error message will be shown to the user
  	// if the PDF does not have a synchronization file
  	if (!dm->pdfSync) {
  	const char* path = tab->filePath;
  	int err = Synchronizer::Create(path, dm->GetEngine(), &dm->pdfSync);
  	if (err == PDFSYNCERR_SYNCFILE_NOTFOUND) {
  	// We used to warn that "No synchronization file found" at this
  	// point if gGlobalPrefs->enableTeXEnhancements is set; we no longer
  	// so do because a double-click has several other meanings
  	// (selecting a word or an image, navigating quickly using links)
  	// and showing an unrelated warning in all those cases seems wrong
  	return false;
  	}
  	if (err != PDFSYNCERR_SUCCESS) {
  	NotificationCreateArgs args;
  	args.hwndParent = win->hwndCanvas;
  	args.msg = _TRA("Synchronization file cannot be opened");
  	ShowNotification(args);
  	return true;
  	}
  	gGlobalPrefs->enableTeXEnhancements = true;
  	}
  	int pageNo = dm->GetPageNoByPoint(Point(x, y));
  	if (!tab->ctrl->ValidPageNo(pageNo)) {
  	return false;
  	}
  	Point pt = ToPoint(dm->CvtFromScreen(Point(x, y), pageNo));
  	AutoFreeStr srcfilepath;
  	int line = 0;
  	int col = 0;
  	int err = dm->pdfSync->DocToSource(pageNo, pt, srcfilepath, &line, &col);
  	if (err != PDFSYNCERR_SUCCESS) {
  	NotificationCreateArgs args;
  	args.hwndParent = win->hwndCanvas;
  	args.msg = _TRA("No synchronization info at this position");
  	ShowNotification(args);
  	return true;
  	}
  	if (!file::Exists(srcfilepath)) {
  	// if the source file is missing, check if it's been moved to the same place as
  	// the PDF document (which happens if all files are moved together)
  	TempStr altsrcpath = path::GetDirTemp(tab->filePath);
  	altsrcpath = path::JoinTemp(altsrcpath, path::GetBaseNameTemp(srcfilepath));
  	if (!str::Eq(altsrcpath, srcfilepath) && file::Exists(altsrcpath)) {
  	srcfilepath.SetCopy(altsrcpath);
  	}
  	}
  	char* inverseSearch = gGlobalPrefs->inverseSearchCmdLine;
  	if (!inverseSearch) {
  	Vec<TextEditor*> editors;
  	DetectTextEditors(editors);
  	if (editors.Size() > 0) {
  	inverseSearch = str::DupTemp(editors[0]->openFileCmd);
  	}
  	}
  	AutoFreeStr cmdLine;
  	if (inverseSearch) {
  	cmdLine = BuildOpenFileCmd(inverseSearch, srcfilepath, line, col);
  	}
  	NotificationCreateArgs args;
  	args.hwndParent = win->hwndCanvas;
  	args.msg = _TRA("Cannot start inverse search command. Please check the command line in the settings.");
  	if (!str::IsEmpty(cmdLine.Get())) {
  	// resolve relative paths with relation to SumatraPDF.exe's directory
  	char* appDir = GetSelfExeDirTemp();
  	AutoCloseHandle process(LaunchProcessInDir(cmdLine, appDir));
  	if (!process) {
  	ShowNotification(args);
  	}
  	} else if (gGlobalPrefs->enableTeXEnhancements) {
  	ShowNotification(args);
  	}
  	return true;
  	}

Additional context
I suggest making the info messages more distinguishable between forward and backward sync failures for better debugging.
E.g. "[source to PDF] No synchronization info at this position" and "[PDF to source] No synchronization info at this position"

• Forward:
  

  sumatrapdf/src/SearchAndDDE.cpp

  Line 652 in ab3bd6f

  args.msg = _TRA("No synchronization info at this position");

• Backward:
  

  sumatrapdf/src/SearchAndDDE.cpp

  Line 560 in ab3bd6f

  args.msg = _TRA("No synchronization info at this position");

Test files
D2_InverseSearch_issue.zip

[unbadfish]

ADD:
In my case, to read the .synctex file, you must (re) open the file by "GBK" or "GB 2312" or "GB 18030" encoding. (They are similar to each other)

[unbadfish]

@kjk , in v3.7.17753, the bug still exists.

[kjk]

unfortunately I don't have a setup to test this.

are you capable of figuring out and testing the fix on your computer?

[unbadfish]

are you capable of figuring out and testing the fix on your computer?

I have cloned this repo, but there are several build errors when build by VS 2022 ...

Please change theþin ext/unrar/cmddata.cpp#L654 to ".". in my computer (code page 936), this would eat the new line 😢

sumatrapdf/ext/unrar/cmddata.cpp

Lines 654 to 655 in ab3bd6f

	// archives created by future versions with higher PACK_MAX_DICTþ
	uint Flags;

[kjk]

That's a code page issue, it's harmless. Please just fix it in your checkout by deleting that line.

[kjk]

should be fixed if you update to latest code

[GitHubRulesOK]

I will simply refer to the question raised by the syctex author (https://tex.stackexchange.com/questions/749419/how-tex-engines-encode-file-names-internally-on-windows) and the response they got !

simple experiments on Windows show that for both pdflatex and xelatex, filenames in the .synctex file are encoded in the system code page (ANSI code page in Microsoft-speak). With a default Windows locale for U.S.A. or Western Europe, that is CP1252.

sample file with no folder name should work in any folder from hex 20 to hex 7E (space) to (~) but no guarantee it will work with £ ¥ or € sync.zip
The system never expecteed to be run outside ASCII named folders

there may be related info in jlaurens/synctex#63

[unbadfish]

@kjk I have fixed this bug, see unbadfish@8c85283 .
Due to commits 68fb791, fde68a4, 390bb1d are useless, please do not commit in next 3 hour, and give me a window to merge my fix and undo these commits. Thanks!

[kjk]

@unbadfish I'll hold off making changes for next 3 hrs