Signal, on Slackware 15.0, stopped working a few days ago, as of Jun 4th, 2026, when installing it from SlackBuilds[1]. It requires a newer glibc library version than what is provided, by default on Slackware. Some users do fix this by upgrading their glibc library packages to the latest testing ones, from Slackware’s site. This, however, might be risky, and will cause all packages compiled on the upgraded machine to never work on any machines without the upgrade. Thus, you might wish to keep your original Slackware glibc packages, but still want Signal to just work. This hack[2] will allow Signal to use a more up-to-date glibc version, without upgrading the OS base libraries; seems to work for me. First, install the new testing glibc package into a root inside /opt, isolated from the rest of the system, then patch the ELF headers, using patchelf, to update the runtime linker and override the linker library search path for all executable and library files inside the Signal package, to make them use the glibc libraries we installed to /opt, instead of the system-provided ones. If you are interested in this, please check the script[2] for details, and info on how to run it. This is definitely a hacky path, but it is a much narrower intervention than updating glibc for your entire system. It is also well isolated from the rest of the system, so harm is minimized. You can easily revert this hack, if you wish. Do not be alarmed if you see warnings about not finding ‘.interp’ sections, they are harmless, and happen because the dynamic linker in shared libraries can not be updated in the ELF binary itself, but is set instead by the actual executable that requests the shared library dynamically.

At the end of this, Signal should run fine, hopefully :)