General Information
On 23rd of September 2025 the following was released:
- ISL Player 4.4.2526.17 for Windows (release_date=2025-09-22, build=1b7849ebcd02135f7f6c6b4523581a2ee8bb918d, platform=win32, os_version=0x06010000-0x7fffffff)
- ISL Player 4.4.2526.17 for MacOSX (release_date=2025-09-22, build=1b7849ebcd02135f7f6c6b4523581a2ee8bb918d, platform=mac, os_version=0x0a0e00-0x1bffff)
- ISL Player 4.4.2526.17 for Linux 64bit (release_date=2025-09-22, build=1b7849ebcd02135f7f6c6b4523581a2ee8bb918d, platform=linux64, os_version=0x030a000000021100-0xffffffffffffffff)
Update availability
All updates have release date set to 2025-09-22. Your ESS will need to be same or higher to be able to update your server. This release is available to all countries except Japan.
Upgrading to new version
Hosted service users please check Upgrading Hosted Service.
Server license users please check Upgrading Server License.
Improvements
ISL Player - Desktop - Upgrade QT to 5.15.11 and raise OS version requirement on Linux (SPECIAL) [ISLPLAYER-279] More
Description
QT library was updated to version 5.15.11. Additionally minimal requirement version for ISL Player on Linux was raised to linux version 3.10 and glibc 2.17.
ISL Player - Desktop - Replace yuv2rgb.neon.S with libyuv (SPECIAL) [ISLPLAYER-308] More
Description
The video plugin used in ISL Player was using yuv2rgb.neo.S library which was now replaced with libyuv library.
ISL Player - Desktop - Update SoundTouch library (SPECIAL) [ISLPLAYER-309] More
Description
The SoundTouch libarary which is used in audio plugin was updated to latest available version (2.4.0).
ISL Player - Desktop - Update FFmpeg library (SPECIAL) [ISLPLAYER-315] More
Description
The FFmpeg library was updated.
ISL Player - Desktop - Update Mbedtls to 2.28.10 (SECURITY) [ISLPLAYER-320] More
Description
Internal mbedTLS library was updated to version 2.28.10.
ISL Player - Desktop - Parse audit events from isr file (FEATURE) [ISLPLAYER-262] More
Description
Added support to ISL Player to decode audit events from a .isr file.
ISL Player - Desktop - Executable LZMA2 support with compression dictionary (FEATURE) [ISLPLAYER-270] More
Description
Support for LZMA2 compression was added to ISL Player.
ISL Player - Desktop - Optimize windows exe configuration (FEATURE) [ISLPLAYER-272] More
Description
Optimized windows exe configuration for ISL Player.
ISL Player - Desktop - Add support for extra dict and extra file (FEATURE) [ISLPLAYER-273] More
Description
Support for extra file was added to launch. Extra file can be used to reduce size of unauthenticated blob. When extra file is used, UA blob only contains command to jump to extra file (has same name as main file but ends with ".extra").
Hashing algorithm in packet generator was upgraded from MD5 to SHA256.
ISL Player - Desktop - Add customization options for custom program icon and custom logo/visual (FEATURE) [ISLPLAYER-274] More
Description
Support for customization was added to ISL Player. We have added new settings for ISL Player customization:
- Icon for ISL Player - this image will serve as the program icon
- Icon package for ISL Player (ZIP) - can contain the following images in the root of the ZIP:
- custom_keyvisual.png: image used in the QuickStartDialog (Size: 64x64)
- custom_name.png: company name image used in the AboutWidget (Size: 80x19)
- custom_logo.png: company logo image used in the AboutWidget (Size: 128x128)
- custom_icon_AxA.png: image used in the program's menu bar and OS taskbar (size depends on OS and settings for that OS). For full support make sure all of the following sizes are set: [ 16, 24, 32, 48, 64, 96, 128, 256, 512]
ISL Player - Desktop - Send scope_web flag on MUX netstart channel (FEATURE) [ISLPLAYER-277] More
Description
Support for ISL Network Start program download channel scope_web flag and user_agent was added. ISL Network Start will run in regular mode (scope_web = true). ISL Light and ISL Player will run downloads in stricter mode (scope_web = false).
ISL Player - Desktop - Move ISL Player to new notarization schema (FEATURE) [ISLPLAYER-278] More
Description
New notarization scheme and update QT.
ISL Player - Desktop - Add support for allowed extracted file names and CRC32 checksum (FEATURE) [ISLPLAYER-280] More
Description
Support for CRC32 checksum for extra file was added on Windows and it's now mandatory. In case the checksum is not correct it will spawn an error and prevent program from running. Additionally only the following extracted files are allowed in the unsigned part of the executable:
- configuration.ini
- cmdline.txt
ISL Player - Desktop - Switch to new hefa crash watch framework (FEATURE) [ISLPLAYER-281] More
Description
ISL Player now uses new implementation of crash framework which is used for detecting the crashes of the application.
ISL Player - Desktop - update hefa watchdog functionality (DEFECT) [ISLPLAYER-284] More
Description
The new watchdog functionality was changed:
- added new function that switches id of main thread to current thread. Main thread is used when dumping watchdog crashes
- fixed an issue where first check of main thread was performed after 60s and not 90s
- increased scheduler and watch timeouts from 90s to 120s
- increased default timeouts from 90s to 120s
ISL Player - Desktop - Add toggle for legacy logs and constexpr implementation (FEATURE) [ISLPLAYER-286] More
Description
Legacy logs can now be controlled using a boolean toggle. Before the legacy logs were controlled by filters but this also caused that logs were completely parsed and data inserted before filters were applied and then the logs were discarded. Now the value is firstly checked in order to eliminate parsing and then discarding of logs.
A new implementation of log format was added that parses log format at compile time and are used at runtime to insert the available arguments. The log format is now also checked at compile time.
ISL Player - Desktop - Add ecdh_ctx log key to mbedTLS log line (FEATURE) [ISLPLAYER-300] More
Description
The log line of ISL Player now includes ecdh_ctx log key which shows which algorithm was used to establish the shared secret.
ISL Player - Desktop - Update logo ISL Online powered by PDQ (FEATURE) [ISLPLAYER-311] More
Description
Updated default ISL Player logo to include powered by PDQ.
ISL Player - Desktop - AutoTransport add SNI to permissive SSL mode (FEATURE) [ISLPLAYER-318] More
Description
AutoTransport methods wsstun-direct, wsstun-proxy, https-direct, https-proxy were fixed to use SNI (send connection hostname in SSL handshake) in order to improve compatibility with third party load balancers like Cloudflare.
ISL Player - Desktop - Send my_hash on MUX netstart channel (FEATURE) [ISLPLAYER-321] More
Description
"my_hash" argument is now separated from query in netstart "start-boot" command. "my_hash" is reinserted into query on ISL Conference Proxy if it supports new protocol ("my_md5" -> "my_hash"). When chunk that is already available in local cache is received it is now overwritten.
ISL Player - Desktop - Move crash tests to hefa and implement watchdog function (FEATURE) [ISLPLAYER-322] More
Description
A new watchdog function was implemented, that will issue reset counter on specific executor to prevent an app being killed.
ISL Player - Desktop - Improve flags window by adding a filter to show the changed flags only (FEATURE) [ISLPLAYER-323] More
Description
In the flags window a new section was added which only displays the flags that were changed by the user.
ISL Player - Desktop - Add configuration static to package on MacOS (DEFECT) [ISLPLAYER-275] More
Description
ISL Player installation on macOS failed in a beta version of the application. The issue was missing launch part in the program script. The launch part was added, application will now be correctly installed.
The defect was fixed.
ISL Player - Desktop - Remove question mark (DEFECT) [ISLPLAYER-282] More
Description
Users sometimes experienced an issue when clicking on question mark button located in the top right which resulted in no action. The question mark button was removed.
The defect was fixed.
ISL Player - Desktop - Add missing libs installation in installer (DEFECT) [ISLPLAYER-283] More
Description
When installing ISL Player the application installer now detects if there are any missing system libraries needed to install the application. If missing libraries are detected a dialog is spawned which asks the user if he wants to install the missing libraries. If confirmed the ISL Player installer will proceed with installation of the application.
The defect was fixed.
ISL Player - Desktop - Exe details are showing incorrect version when downloading application using /download (DEFECT) [ISLPLAYER-288] More
Description
Users on Windows experienced an issue where ISLPlayer.exe was filled with incorrect information about version and other information. The functionality was redesigned and the issue is no longer reproducible.
The defect was fixed.
ISL Player - Desktop - Playing recording directly after recording of session is not displayed correctly if user changes remote resolution (DEFECT) [ISLPLAYER-290] More
Description
Users experienced an issue where recording was not displayed correctly when playing a recording directly after recording of a session when user changed remote resolution in session. The functionality was redesigned and the issue is no longer reproducible.
The defect was fixed.
ISL Player - Desktop - Increase timeout on "watcher" watchdog thread (DEFECT) [ISLPLAYER-292] More
Description
Watchdog implementation of Windows was updated with:
- updated timeouts
- added log for thread ids
- added NOX on failed thread create
- removed use of rand function that uses enter critical section
The time for unresponsive scheduler check is 2,5 min - before it was 2min. The time for unresponsive watcher check is now 10 min - before it was 2min. We now report also the wd count that was reached when watchdog crashed.
ISL Player - Desktop - Add LARGEADDRESSAWARE flag (DEFECT) [ISLPLAYER-295] More
Description
Users experienced an issue where ISL Player would crash when over 1 GB of ram was allocated in ISL Player and a recording was opened. The functionality was redesigned and the issue is no longer reproducible.
The defect was fixed.
ISL Player - Desktop - Can not open ISL Player when downloaded from /start on macOS (DEFECT) [ISLPLAYER-296] More
Description
Users experienced an issue where they could not open ISL Player on macOS when ISL Player was downloaded via /start. The functionality was redesigned and the issue is no longer reproducible.
The defect was fixed.
ISL Player - Desktop - Fix icon copy in secure part (DEFECT) [ISLPLAYER-297] More
Description
On macOS in some cases the application icons were not copied in a secure manner. Copying of application icons was redesigned, so they are now copied securely.
The defect was fixed.
ISL Player - Desktop - Change dots to underscores for filename on Linux (DEFECT) [ISLPLAYER-301] More
Description
In previous versions the filename version was delimited with dots. This caused an issue when build number was less then 10 as the application opened as text editor. The dots were now replaced with underscores and this now always executes the application correctly.
The defect was fixed.
ISL Player - Desktop - Incorrect exe information (DEFECT) [ISLPLAYER-302] More
Description
Some of the dlls and executables that ISL Player is using were showing incorrect version information in properties of a file. Properties now show the correct version.
The defect was fixed.
ISL Player - Desktop - Exe details are showing incorrect version (DEFECT) [ISLPLAYER-304] More
Description
The ISL Player application has incorrect copyright and version written in details. The details are now showing the correct copyright and correct version.
The defect was fixed.
ISL Player - Desktop - User avatar images missing (DEFECT) [ISLPLAYER-305] More
Description
In previous versions the recording was missing avatar images. The functionality was redesigned and the issue is no longer reproducible.
The defect was fixed.
ISL Player - Desktop - FFmpeg .dlls details are empty (DEFECT) [ISLPLAYER-306] More
Description
In previous version details of some dll files in ISL Player directory were empty. The functionality was redesigned and the issue is no longer reproducible.
The defect was fixed.
ISL Player - Desktop - Exe details are showing incorrect version (DEFECT) [ISLPLAYER-310] More
Description
ISL Player was showing incorrect version when checking properties of the install and uninstall files. The correct version is now written.
The defect was fixed.
ISL Player - Desktop - WinINet http proxy bypass and force_auth options (DEFECT) [ISLPLAYER-313] More
Description
Two options were added to AutoTransport which affect wininet-http and wininet-https transports:
- http_proxy_bypass: configure which hostnames should (or not) use direct connection without proxy, use <-loopback> to allow localhost connections through proxy
- http_proxy_force_auth: immediately start with configured user+password when connecting, used to resolve a problem when Windows system account is not allowed to connect through proxy but http_proxy_user is allowed and proxy is using Windows integrated authentication
ISL Player - Desktop - Use short explicit hex code SSL cipher suites (DEFECT) [ISLPLAYER-314] More
Description
MbedTLS cipher suite used was simplified to be similar to server OpenSSL cipher suite. Additionally the following ciphers were removed:
- DHE
- ECDH
- CAMELLIA
- 3DES (except TLS-RSA-WITH-3DES-EDE-CBC-SHA)
ISL Player - Desktop - AutoTransport SSL protocol and ciphers setting (DEFECT) [ISLPLAYER-316] More
Description
Options "ssl_protocol" and "ssl_ciphers" were added to AutoTransport. Besides legacy OpenSSL format, the options support numeric hex codes:
- ssl_protocol: "0x0301-0x10000" for TLS 1.0 profile and "0x0303-0x10000" for TLS 1.2 profile. 3-byte hex code "0x10000" is interpreted as no bound.
- ssl_ciphers: can now be specified using a simple numeric hex code list: "0x1302 0x1301 ..."
ISL Player - Desktop - Always enable TLS when opening AT MUX channel (DEFECT) [ISLPLAYER-317] More
Description
In previous version some mux connection channels were not protected by TLS session. TLS session is now enabled on all mux channels.
The defect was fixed.
ISL Player - Desktop - Adjust launch to support options '8' on macOS correctly (DEFECT) [ISLPLAYER-319] More
Description
On macOS the resources could be injected to be copied by launcher to the destination folder. That was due to this operation being appended in the unsingned part of the package. The copy operation must now first be allowed in the signed part of the package in order to be executed in the unsigned part.
The defect was fixed.
ISL Player - Desktop - Fix PAC parser for multiple returned HTTP proxy addresses (DEFECT) [ISLPLAYER-324] More
Description
In previous versions if users had multiple proxies defined in the PAC file in some cases the incorrect proxy was selected. PAC file parser was redesigned and now the correct proxy is used.
The defect was fixed.
ISL Player - Desktop - Fix HTTPS proxy for wsstun-proxy (DEFECT) [ISLPLAYER-325] More
Description
In previous versions where users used wsstun-proxy it was using HTTP proxy instead of HTTPS proxy. The incorrect usage was changed, so with wsstun-proxy type of connection the HTTPS proxy is now used.
The defect was fixed.
ISL Player - Desktop - Application menu entry does not have icon on Linux (DEFECT) [ISLPLAYER-327] More
Description
Users experienced an issue on Linux where an icon for ISL Player was not shown. The functionality was redesigned and the issue is no longer reproducible.
The defect was fixed.
ISL Player - Desktop - User can not upgrade ISL Player on Linux via "Check for updates" and "About me" window (DEFECT) [ISLPLAYER-328] More
Description
Users on Linux experienced an issue where they could not perform update of ISL Player within the program. The functionality was redesigned and the issue is no longer reproducible.
The defect was fixed.