516162 2026-02-17 20:29:41 +0000 Tesseract library is not found 2026-04-16 13:33:33 +0000 1 1 2 Applications Spectacle General 6.6.0 Fedora RPMs Linux RESOLVED FIXED VHI major --- 1 farchord noahadvs agurenko fred.dumois kde madness742 nate ngompa nivaca nucleo pallaswept pg_forums rikmills slartibart70 https://invent.kde.org/plasma/spectacle/-/commit/13b0be099e7abe9bbb17b90e62c2e83afb248db7 6.7.0 0 oldest_to_newest 2495509 0 farchord 2026-02-17 20:29:41 +0000 *** If you're not sure this is actually a bug, instead post about it at https://discuss.kde.org If you're reporting a crash, attach a backtrace with debug symbols; see https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports Please remove this comment after reading and before submitting - thanks! *** SUMMARY On Fedora 43 and up, loading spectacle works, but on load, we get the following error in the logs: spectacle: Unable to load Tesseract candidate "libtesseract.so.5" : "Cannot load library libtesseract.so.5: libtesseract.so.5: cannot open shared object file: No such file or directory" spectacle: Unable to load Tesseract candidate "libtesseract.so.4" : "Cannot load library libtesseract.so.4: libtesseract.so.4: cannot open shared object file: No such file or directory" spectacle: Unable to load Tesseract candidate "libtesseract.so" : "Cannot load library libtesseract.so: libtesseract.so: cannot open shared object file: No such file or directory" spectacle: Unable to locate a suitable Tesseract shared library spectacle: Tesseract runtime library not available Fedora uses Tesseract 5.5.2, which includes a libtesseract.so.5.5 and libtesseract.so.5.5.2, but no .5, .4 or .so. STEPS TO REPRODUCE 1. On Fedora, launch spectacle from console 2. The app will start, but the above answer will show in the log. OBSERVED RESULT App starts, but an error shows in the log (And the associated features using tesseract do not work) EXPECTED RESULT No errors, and image scanning works SOFTWARE/OS VERSIONS Operating System: Fedora Linux 44 KDE Plasma Version: 6.6.0 KDE Frameworks Version: 6.23.0 Qt Version: 6.10.2 Kernel Version: 6.19.0-301.fc44.x86_64 (64-bit) Graphics Platform: Wayland Processors: 24 × AMD Ryzen 9 9900X3D 12-Core Processor Memory: 128 GiB of RAM (125.3 GiB usable) Graphics Processor: AMD Radeon RX 7900 XT Manufacturer: Gigabyte Technology Co., Ltd. Product Name: X870E AORUS MASTER X3D ICE System Version: Default string-WCP-ADO-XT2 ADDITIONAL INFORMATION 2495533 1 noahadvs 2026-02-17 22:03:01 +0000 It seems that the logic for loading tesseract may not be robust enough. In case there's someone who can figure out a fix before me, here's some info about the relevant code. In spectacle/src/TesseractRuntimeLoader.cpp, TesseractRuntimeLoader::loadLocked() calls TesseractRuntimeLoader::candidateLibraryNames() to get a list of library names. >QStringList TesseractRuntimeLoader::candidateLibraryNames() const >{ > return {QStringLiteral("libtesseract.so.5"), QStringLiteral("libtesseract.so.4"), QStringLiteral("libtesseract.so")}; >} In TesseractRuntimeLoader::loadLocked(), "m_library" is an instance of QLibrary (https://doc.qt.io/qt-6/qlibrary.html). >bool TesseractRuntimeLoader::loadLocked() >{ > const auto candidates = candidateLibraryNames(); > for (const QString &candidate : candidates) { > m_library.setFileName(candidate); > m_library.setLoadHints(QLibrary::ExportExternalSymbolsHint | QLibrary::PreventUnloadHint); > > if (!m_library.load()) { > qCWarning(SPECTACLE_LOG) << "Unable to load Tesseract candidate" << candidate << ':' << m_library.errorString(); > continue; > } > > qCInfo(SPECTACLE_LOG) << "Attempting to use Tesseract library" << candidate; > > if (!resolveSymbols()) { > m_library.unload(); > continue; > } > > if (!validateLoadedVersion()) { > m_library.unload(); > continue; > } > > m_loaded = true; > qCInfo(SPECTACLE_LOG) << "Loaded Tesseract runtime library from" << m_library.fileName(); > return true; > } > > qCWarning(SPECTACLE_LOG) << "Unable to locate a suitable Tesseract shared library"; > return false; >} 2495539 2 bug-janitor 2026-02-17 22:15:03 +0000 A possibly relevant merge request was started @ https://invent.kde.org/plasma/spectacle/-/merge_requests/511 2495646 3 slartibart70 2026-02-18 10:10:28 +0000 in the meantime, doing this helps: cd /usr/lib64 ln -s libtesseract.so.5.5 libtesseract.so.5 2495741 4 arojas 2026-02-18 13:16:20 +0000 *** Bug 516203 has been marked as a duplicate of this bug. *** 2495958 5 nivaca 2026-02-18 22:10:26 +0000 (In reply to slartibart70 from comment #3) > in the meantime, doing this helps: > > cd /usr/lib64 > ln -s libtesseract.so.5.5 libtesseract.so.5 This worked for me. Thanks. 2500959 6 noahadvs 2026-03-05 17:53:44 +0000 Git commit 921620e5153b2eb103c1633fee3995b187bd08db by Noah Davis. Committed on 05/03/2026 at 15:07. Pushed by ndavis into branch 'master'. Fix tesseract not being found on Fedora Now it tries to match any library called "tesseract" See https://doc.qt.io/qt-6/qlibrary.html#details for how this should work. FIXED-IN: 6.6.1 M +5 -1 src/TesseractRuntimeLoader.cpp https://invent.kde.org/plasma/spectacle/-/commit/921620e5153b2eb103c1633fee3995b187bd08db 2500961 7 noahadvs 2026-03-05 17:54:40 +0000 Git commit 89538f014de81ce15f70a3e8b1125648ef5d37ef by Noah Davis. Committed on 05/03/2026 at 17:54. Pushed by ndavis into branch 'Plasma/6.6'. Fix tesseract not being found on Fedora Now it tries to match any library called "tesseract" See https://doc.qt.io/qt-6/qlibrary.html#details for how this should work. FIXED-IN: 6.6.1 (cherry picked from commit 921620e5153b2eb103c1633fee3995b187bd08db) Co-authored-by: Noah Davis <noahadvs@gmail.com> M +5 -1 src/TesseractRuntimeLoader.cpp https://invent.kde.org/plasma/spectacle/-/commit/89538f014de81ce15f70a3e8b1125648ef5d37ef 2500962 8 noahadvs 2026-03-05 17:55:45 +0000 Changed the fixed-in version to 6.6.3 because the patch missed 6.6.1 and 6.6.2, but I forgot to change the commit message 2506333 9 pg_forums 2026-03-26 18:42:38 +0000 This isn't working correctly in spectacle 6.6.3-1 on Fedora 43. On a system which has the 'tesseract-libs' package installed (and therefore has library files at '/usr/lib64/libtesseract.so.5.5.2' and '/usr/lib64/libtesseract.so.5.5', but no file simply called 'libtesseract.so'), Spectacle reports that OCR is not available. Starting Spectacle from the command line gives the messages: ``` spectacle: Unable to load Tesseract candidate "tesseract" : "Cannot load library tesseract: tesseract: cannot open shared object file: No such file or directory" spectacle: Unable to locate a suitable Tesseract shared library spectacle: Tesseract runtime library not available ``` Looking at the documentation of the QLibrary class, does it actually do what we need here, i.e. to find 'libtesseract.so.5.5" or 'libtesseract.5.5.2.so'? According to the docs, it "tries the name with different platform-specific file prefixes, like "lib" on Unix and Mac ... and suffixes, like ".so" on Unix...". So, if you tell it to look for 'tesseract', you'd expect it to find 'libtesseract.so', but there's nothing to say that it will find files with version-specific suffices like 'libtesseract.so.5.5" 2506385 10 farchord 2026-03-27 01:28:13 +0000 Can confirm: spectacle: Unable to load Tesseract candidate "tesseract" : "Cannot load library tesseract: tesseract: cannot open shared object file: No such file or directory" spectacle: Unable to locate a suitable Tesseract shared library spectacle: Tesseract runtime library not available 2506786 11 pallaswept 2026-03-28 20:57:22 +0000 +1. I have a live opensuse tumbleweed image with 6.6.0 and another with 6.6.3. Installing libtesseract and a language pack will get it working on 6.6.0, the exact same tesseract packages installed on the image with 6.6.3 fails as described above. I also had it working on the host prior to the update to 6.6.3 and it is no longer working there. Probable dupes, which were added since 6.6.3: https://bugs.kde.org/show_bug.cgi?id=518039 https://bugs.kde.org/show_bug.cgi?id=517900 2506789 12 pallaswept 2026-03-28 21:36:24 +0000 (In reply to pg_tips from comment #9) > Looking at the documentation of the QLibrary class, does it actually do what > we need here, i.e. to find 'libtesseract.so.5.5" or 'libtesseract.5.5.2.so'? Seems you're right. Qt is testing the 'lib' prefix, and does test the .so suffix, but does not provide any wildcard/glob searching of the name or the extension. I have /usr/lib64/libtesseract.so.5 -> libtesseract.so.5.0.5 If I do sudo ln -s /usr/lib64/libtesseract.so.5.0.5 %FILENAME /usr/lib64/libtesseract.so works /usr/lib64/tesseract.so works /usr/lib64/tesseract.so.5 fails /usr/lib64/tesseract5.so fails 2506792 13 pallaswept 2026-03-28 22:19:19 +0000 And here's our root cause, a 7 year old bug in tesseract: https://github.com/tesseract-ocr/tesseract/issues/2749#issuecomment-4148915185 2506867 14 nivaca 2026-03-29 14:51:38 +0000 It is now working for me. Spectacle: 6.6.3 KDE Frameworks: 6.24.0 Qt: Using 6.10.2 and built against 6.10.2 Fedora Linux 43 (KDE Plasma Desktop Edition) (Wayland) Build ABI: x86_64-little_endian-lp64 Kernel: linux 6.19.9-200.fc43.x86_64 2506870 15 pg_forums 2026-03-29 15:19:47 +0000 (In reply to Nicolas Vaughan from comment #14) > It is now working for me. > > Spectacle: 6.6.3 Is that version 6.6.3-2 of the spectacle package? That has a patch by the Fedora maintainers to work around the bug. 2506871 16 nivaca 2026-03-29 15:30:13 +0000 Yes: spectacle.x86_64 1:6.6.3-2.fc43 (In reply to pg_tips from comment #15) > (In reply to Nicolas Vaughan from comment #14) > > It is now working for me. > > > > Spectacle: 6.6.3 > > Is that version 6.6.3-2 of the spectacle package? That has a patch by the > Fedora maintainers to work around the bug. Yes: spectacle.x86_64 1:6.6.3-2.fc43 2506913 17 o.g.m.belleux 2026-03-29 18:59:50 +0000 Confirm on opensuse leap 16 spectacle: Unable to load Tesseract candidate "tesseract" : "Impossible de charger la bibliothèque tesseract : tesseract: cannot open shared object file: No such file or directory" spectacle: Unable to locate a suitable Tesseract shared library spectacle: Tesseract runtime library not available Operating System: openSUSE Leap 16.0 KDE Plasma Version: 6.6.3 KDE Frameworks Version: 6.24.0 Qt Version: 6.10.2 Kernel Version: 6.12.0-160000.27-default (64-bit) Graphics Platform: Wayland Processors: 8 × 11th Gen Intel® Core™ i7-1165G7 @ 2.80GHz Memory: 16 Gio of RAM (15.4 Gio usable) Graphics Processor: Intel® Iris® Xe Graphics Manufacturer: Notebook Product Name: NLx0MU 2507007 18 rikmills 2026-03-30 09:18:24 +0000 Can also confirm in Kubuntu 26.04. Same issue. Cannot find or load the versioned libraries 2507009 19 rikmills 2026-03-30 09:33:06 +0000 (In reply to Rik Mills from comment #18) > Can also confirm in Kubuntu 26.04. > > Same issue. Cannot find or load the versioned libraries i.e. In Ubuntu cannot not find/load libtesseract.so.5 or libtesseract.so.5.0.5 2507216 20 pallaswept 2026-03-31 08:47:17 +0000 Apparently a summary of my above posts and the attached links, is in order, so... There is no need for "works for me" or "doesn't work here" posts. The nature of the problem is well understood, and we already know where it does and does not work. There are three bugs interacting here: - Tesseract built with cmake (fedora) has the wrong library soname (and so, mis-named symlink to the library) - Tesseract built with autotools (debian, suse, arch) has the wrong library filename - Spectacle searches for the wrong name (because there is no right name, because of the above bugs) The fix will be to first fix library naming of tesseract in each build system, and then to fix spectacle to search for the resulting libraries. Alternatively, for a permanent workaround if tesseract will not be fixed, spectacle could search for the various possible library names for all distros. The most portable way of doing this is return {QStringLiteral("tesseract.so.5.5"), QStringLiteral("tesseract.so.5"), QStringLiteral("tesseract.so.4"), QStringLiteral("tesseract")}; This will work across all distros and all compatible releases of tesseract from either build system. For KDE I would recommend this course forward, as it will work both immediately and after tesseract is fixed and that fix rolls out, which may take some time, may be out of sync with KDE, or may never happen at all. @KDE: This is what happens when developers ignore legit bug reports because they don't like the user who reported the bug. 2507250 21 rikmills 2026-03-31 14:13:56 +0000 (In reply to Noah Davis from comment #6) > Git commit 921620e5153b2eb103c1633fee3995b187bd08db by Noah Davis. K/Ubuntu have had to revert this commit in packaging to fix this bug. 2510310 22 nicolas.fella 2026-04-16 09:39:45 +0000 Git commit 13b0be099e7abe9bbb17b90e62c2e83afb248db7 by Nicolas Fella. Committed on 16/04/2026 at 09:35. Pushed by nicolasfella into branch 'master'. Properly link against tesseract When using QLibrary to load a library at runtime, QLibrary finds the library by looking for a file that has a platform dependent prefix and suffix added to a given base name (e.g., "tesseract" -> "libtesseract.so"). If a Linux distro doesn't have a file called "libtesseract.so", the library won't be found even if "libtesseract.so.5" exists unless you add logic to also check for that file. Tesseract has a bug where different ways of building it can generate different library file names (https://github.com/tesseract-ocr/tesseract/issues/2749). We could work around this by checking the file names used by different distros, but we've decided that it's better to link to the tesseract library to avoid this problem entirely. We generally prefer requiring libraries anyway to avoid situations where users don't see a feature because they didn't know they needed to install an optional dependency. That situation is unfortunately still not 100% avoidable since Tesseract language packs are optional and Tesseract doesn't work without them. M +3 -0 CMakeLists.txt M +1 -1 src/CMakeLists.txt M +36 -67 src/OcrManager.cpp M +4 -5 src/OcrManager.h D +0 -189 src/TesseractRuntimeLoader.cpp D +0 -76 src/TesseractRuntimeLoader.h https://invent.kde.org/plasma/spectacle/-/commit/13b0be099e7abe9bbb17b90e62c2e83afb248db7