General Information
On 11th of February the following was released:
- ISL Tester 5.0.2551.18 for Windows (release_date=2026-02-11, build=b35f3084646d973a9b9a71e4afe9ae3c9b2c6c04, platform=win32, os_version=0x0a000000-0x7fffffff)
- ISL Tester 5.0.2551.18 for macOS (release_date=2026-02-11, build=b35f3084646d973a9b9a71e4afe9ae3c9b2c6c04, platform=mac, os_version=0x0e0000-0x2effff)
- ISL Tester 5.0.2551.18 for Linux (release_date=2026-02-11, build=b35f3084646d973a9b9a71e4afe9ae3c9b2c6c04, platform=linux64, os_version=0x050fc10000022300-0xffffffffffffffff)
All updates have release date set to 2026-02-11. 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.
IMPORTANT:
- Minimal operating system requirement on Windows for ISL Tester application was raised from Windows 7 to Windows 10.
- Minimal operating system requirement for ISL Tester on macOS was raised to macOS 14.
- Minimal operating system requirement for ISL Tester on Linux was raised to require glibc 2.35.
Improvements
ISL Tester - Desktop - Set build os_version maximum to macOS 46.x (SPECIAL) [ISLTESTER-112] More
Description
Upper limit for os_version for macOS was changed from 0x1bffff to 0x2effff (macOS 46.X).
ISL Tester - Desktop - Raise minimal OS requirement on Windows from Windows 7 to Windows 10 (SPECIAL) [ISLTESTER-114] More
Description
Minimal operating system requirement on Windows for ISL Tester application was raised from Windows 7 to Windows 10.
ISL Tester - Desktop - Raise minimal required version of Windows 10 to Windows 10 version 1809 (SPECIAL) [ISLTESTER-120] More
Description
Minimal required OS version was additionally raised from Windows 10 to Windows 10 version 1809 (Build 17763).
ISL Tester - Desktop - Raise os_version version of ISL programs to macOS 14 (SPECIAL) [ISLTESTER-98] More
Description
Minimum operating system requirement for ISL Tester on macOS was raised to macOS 14.
ISL Tester - Desktop - Update Mbedtls to 2.28.10 (SECURITY) [ISLTESTER-82] More
Description
Internal mbedTLS library was updated to version 2.28.10.
ISL Tester - Desktop - AutoTransport SSL protocol and ciphers setting (FEATURE) [ISLTESTER-100] 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 Tester - Desktop - WinINet http proxy bypass and force_auth options (FEATURE) [ISLTESTER-102] 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 Tester - Desktop - LZMA2 support (FEATURE) [ISLTESTER-103] More
Description
Support for LZMA1 and LZMA2 compression was added to ISL Tester.
ISL Tester - Desktop - Switch desktop clients to new hefa crash watch framework (FEATURE) [ISLTESTER-104] More
Description
In some cases if ISL Tester application crashed and users were using Intel graphics card the crash report was not sent to ISL Conference Proxy. Crash handling was changed and now crash reports are sent also when users have Intel graphics card.
The defect was fixed.
ISL Tester - Desktop - Move crash tests to hefa and implement watchdog function (FEATURE) [ISLTESTER-105] More
Description
A new watchdog function was implemented, that will issue reset counter on specific executor to prevent an app being killed.
ISL Tester - Desktop - Add common crash dump dialog class (FEATURE) [ISLTESTER-106] More
Description
Crash options for intentionally crashing the application was extended. The list now offers most common crash options.
ISL Tester - Desktop - AutoTransport add SNI to permissive SSL mode (FEATURE) [ISLTESTER-109] 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 Tester - Desktop - Send my_hash on MUX netstart channel (FEATURE) [ISLTESTER-115] 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 Tester - Desktop - Raise signed format version for launchpkt (FEATURE) [ISLTESTER-116] More
Description
Configuration and command line arguments are now written in the unauthenticated blob part of the executable. Since the size of unauthenticated blob is limited, if the data exceeds the limitation the old style of signing of application is used.
ISL Tester - Desktop - New connection_keys file holding the connection certificates (FEATURE) [ISLTESTER-118] More
Description
In the ISL Tester folder a new file called connection_keys was added, which holds certificates that are used to establish a secure connection with ISL Conference Proxy. For now this file is not used.
ISL Tester - Desktop - Enable automatic reconnect by default (FEATURE) [ISLTESTER-60] More
Description
Automatic reconnect is now enabled by default.
ISL Tester - Desktop - Use URL query parameter instead of Cookie for SA GRID ID in HTTP tunnels (FEATURE) [ISLTESTER-61] More
Description
HTTP tunnels will now use URL query parameter CPLB=<serverid> instead of cookie CPLBF=<serverid> when connecting to single-address GRID. Affected transports:
- wininet-http
- wininet-https
- httpt-direct
- httpt-proxy
Note: first connection does not pass CPLB or CPLBF, but header "Server: ... \-X-.icp.test" is used to determine X==<serverid> for subsequent connections.
instead of cookie CPLBF= when connecting to single-address GRID. Affected transports: - wininet-http - wininet-https - httpt-direct - httpt-proxy Note: first connection does not pass CPLB or CPLBF, but header "Server: ... \-X-.icp.test" is used to determine X== for subsequent connections.
ISL Tester - Desktop - Executable LZMA2 support with compression dictionary (FEATURE) [ISLTESTER-64] More
Description
LZMA2 compression is now used in ISL Tester. LZMA2 compression dictionary for unauthenticated blob is now used on Windows.
ISL Tester - Desktop - Add support for extra file (FEATURE) [ISLTESTER-65] 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 Tester - Desktop - Add support for allowed extracted file names (FEATURE) [ISLTESTER-70] 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
ISL Tester - Desktop - Georeconnect for Single Address GRID (FEATURE) [ISLTESTER-72] More
Description
Several changes were implemented to allow optimizing client connections in single address GRIDs where client DNS servers do not properly transfer client's IP address to ISL Conference Proxy (ICP):
"Check-Address: 1" header will be sent to ICP when doing geo reconnect to notify ICP that geo reconnect with server address in "Address-Reconnect" is supported
"Service-Reconnect: 1" header will be sent to ICP when doing service reconnect to notify ICP that service reconnect with geo reconnect is supported
"Address-Reconnect" response header will be handled as the new server address in the reconnect service reconnect and geo reconnect are now combined into the same event and executed at the same time:
- update service address in configuration, then - reconnect to new server address
ISL Tester - Desktop - Add toggle for legacy logs and constexpr implementation (FEATURE) [ISLTESTER-75] 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 Tester - Desktop - Add ecdh_ctx log key to mbedTLS log line (FEATURE) [ISLTESTER-88] More
Description
The log line of ISL Tester now includes ecdh_ctx log key which shows which algorithm was used to establish the shared secret.
ISL Tester - Desktop - Show both user-friendly and technical OS name in ISL Tester (FEATURE) [ISLTESTER-93] More
Description
Added support to display user-friendly and technical OS name in ISL Tester.
ISL Tester - Desktop - Migrate from QT 5 to Qt 6 (FEATURE) [ISLTESTER-95] More
Description
ISL Tester application was updated to use QT 6.10.0.
ISL Tester - Desktop - Use short explicit hex code SSL cipher suites (DEFECT) [ISLTESTER-101] 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 Tester - Desktop - Include CFBundleLocalizations in Info.plist to Support Translated Native Platform Dialogs on macOS (DEFECT) [ISLTESTER-107] More
Description
In previous versions ISL Tester sometimes displayed native platform dialogs. On macOS users noticed an issue where regardless of the OS localization the application would always provide these native dialogs in the English language. The functionality was redesigned and support has been added to all the languages we support.
The defect was fixed.
ISL Tester - Desktop - Exe details are showing incorrect version (DEFECT) [ISLTESTER-108] More
Description
The ISL Tester 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 Tester - Desktop - wmic.exe on Windows 10, version 21H1 is obsolete, replace it with other functions (DEFECT) [ISLTESTER-110] More
Description
In previous versions wmic.exe was used to gather operating system information, as the wmic.exe is obsolete the incorrect operating system information was shown. We have replaced wmic.exe and the issue is no longer reproducible.
The defect was fixed.
ISL Tester - Desktop - Adjust launch to support options '8' on macOS correctly (DEFECT) [ISLTESTER-111] 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 unsigned 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 Tester - Desktop - Fix flags dialog on QT 6.0 (DEFECT) [ISLTESTER-113] More
Description
The style of window where you can control which flags ( functionalities ) are enabled was having an outdated look. The windows style was adjusted to the modern window.
The defect was fixed.
ISL Tester - Desktop - Clicking on boost transport options will create an error (DEFECT) [ISLTESTER-119] More
Description
Users experienced an issue where an error was shown when user wanted to boost a transport option in ISL Tester. The functionality was redesigned and the issue is no longer reproducible.
The defect was fixed.
ISL Tester - Desktop - Fix immediate crash (DEFECT) [ISLTESTER-71] More
Description
Users experienced an issue here ISL Tester would crash upon opening the application. The functionality was redesigned and the issue is no longer reproducible.
The defect was fixed.
ISL Tester - Desktop - Fix wrong ram info on windows (DEFECT) [ISLTESTER-73] More
Description
In the system information window in certain cases the RAM usage and RAM size was showing incorrect values when running ISL Tester. Checking of RAM size and usage was redesigned, the correct values should be displayed.
The defect was fixed.
ISL Tester - Desktop - Reject simple 200 OK to avoid confusion with regular web servers (DEFECT) [ISLTESTER-76] More
Description
In previous version when initiating a connection with ISL Conference Proxy only the return status was checked ( status code 200 ) so the library was checking the same transport. Now in addition to the status code check the content of the returned data is also checked which will fail in case ISL Conference Proxy was not the one who replied and the library will continue to check other transports.
The defect was fixed.
ISL Tester - Desktop - Failed to get correct desktop folder on localized Linux (DEFECT) [ISLTESTER-77] More
Description
In case Linux users had a localized Linux setup the Desktop location is not present in /home/username/Desktop instead the last part is localized to the selected language during install. Checking for users desktop folder was redesigned, it will now query the Linux system to let it know the Desktop location instead of using the default Desktop value.
The defect was fixed.
ISL Tester - Desktop - Fix HTTPS proxy for wsstun-proxy (DEFECT) [ISLTESTER-78] 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 Tester - Desktop - Fix PAC parser for multiple returned HTTP proxy addresses (DEFECT) [ISLTESTER-79] 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 Tester - Desktop - Fix icon copy in secure part (DEFECT) [ISLTESTER-81] 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 Tester - Desktop - Change dots to underscores for filename on Linux (DEFECT) [ISLTESTER-89] 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 Tester - Desktop - Remove WMI errors from output log (DEFECT) [ISLTESTER-92] More
Description
Users experienced an issue where WMI errors were shown in ISL Tester logs. We added support via "ignore_errors" (default value is false) to remove WMI errors to the get_props method that queries the WMI data.
The defect was fixed.
ISL Tester - Desktop - Exe details are showing incorrect version (DEFECT) [ISLTESTER-94] More
Description
ISL Tester was showing incorrect version when checking properties of the install and some other executable files. The correct version is now written.
The defect was fixed.
ISL Tester - Desktop - Unify mini crashdump (DEFECT) [ISLTESTER-99] More
Description
Fixed an issue where the crashdump content was not filled correctly on MacOS. The MacOS crashdumps were unified with the specification, and will now contain more information about the crash and agent.
The defect was fixed.
ISL Tester - Desktop - Make QT 6.10 work on first Windows 10 (DEFECT) [ISLTESTER-121] More
Description
Users experienced an issue in previous version where they were not able to use ISL Tester on Windows 10 version 1803 (Build 17134) or older. We have redesigned the functionality and users on any Windows 10 version are able to use ISL Tester now.
The defect was fixed.