I went through your last message and it occurred to me that you don't use fpcupdeluxe for setting up the FPC and Lazarus combo.
That is correct. I do things manually (from scratch and pristine machine).
I only went to the fcpupdeluxe way because it seemed easier than going through 'traditional' installation as the docs about doing that are somewhat 'lacking', to put it mildly.
On occasion I do use fpcdeluxe on a new (FPC supported) system as that will allow me to skip the step of cross compiling first in order to create a native compiler (fpcdeluxe can be faster/quicker than me supporting a new introduced target) but that mostly because of laziness

One thing that I think is definitely a pro for using fpcdeluxe is that it also provides all necessary tools (binutils etc) so that you can skip building those yourself (it can be a daunting task on some platforms).
The general approach is to use a FPC (precompiled) distributed package (whether provided by Free Pascal downloadplaces) or your package manager (if there is any).
But, I dislike that approach of installing precompiled binaries as doing also will dictate where everything is located and that can cause serious headaches when dealing with multiple installations of FPC and/or Lazarus, not to mention cross-compiling.
It would be really great if you roughly describe the way you are doing it and maybe provide me with some links to docs, so I can try the installation your way.
Before going into details on that, please bear in mind that your issue seem to be related to the configuration/setup of Lazarus (due to my lack of knowledge with these kind of errors I am unable to tell if it is something simple that can be fixed based on some simple checks or if there is a bigger underlying issue).
The way that I personally use to install things is not documented anywhere though I used existing documentation (wiki and buildfaq) to get myself familiar with the build system, available platforms and their additional build options if any, required binutils, cross-compilation etc.
I do not have a problem sharing a manual installation process but in the process it might bore you to death. My setup is pretty uncommon in that it works for multiple platforms at the same time so, I am unable to copy/share things verbatim (so that will take some time in case you require detailed instructions).
If you allow, then let me/us take a step back first by asking a few questions.
1.
When you started your freshly installed Lazarus for the first time (you might be able to see that window later as well in case Lazarus thinks there are issues with its setup) there would have been a popup window named "configure Lazarus IDE). For more details/pictures see
https://forum.lazarus.freepascal.org/index.php?topic=61185.0Did you setup the configuration correctly there ?
If you want to go into the nitty gritty details then the file used to store those settings is located in your lazcfg directory and is named "environmentoptions.xml"
2.
Did or have you ever used your package manager or Debian package file from Free Pascal downloads for installing FPC/Lazarus ?
If you have, then that can cause issues with FPCDeluxe (but also for a manual build) as there are configuration files in place that are able to mess up your FPC/Lazarus setup (even after removal as it requires manual labor to be able to do it properly)
As a very raw version of my manual builds:
- Determine which FPC version you wish to build. For example sake: v3.2.2
- Determine bootstrap compiler version (previous dot release). For 3.2.2 that would be 3.2.0
- Download the FPC 3.2.0 archive for your host system. For example sake we are on Linux-x86-64, Thus,
https://sourceforge.net/projects/freepascal/files/Linux/3.2.0/fpc-3.2.0-x86_64-linux.tar- Extract the bootstrap compiler executable (ppcx64) that is required. It is located in the tar file at fpc-3.2.0-x86_64-linux/binary.x86_64-linux.tar/base.x86_64-linux.tar.gz/lib/fpc/3.2.0/ppcx64
- Download and extract source-code for compiler version you wish to build, f.e.
https://sourceforge.net/projects/freepascal/files/Source 3.2.2/fpc-3.2.2.source.tar.gz (alternatively you can use git to clone the gitlab repository and checkout the 3.2.2 branch).
- Build the FPC compiler using the bootstrap compiler, e.g. make clean all install PP="/wherever/your/ppcx86_64/executable/is/located/but/please/avoid/having/it/in/your/searchpath" . Use additional make options if required.
- optionally build a cross compiler using the FPC executable of your freshly build fpc 3.2.2 with using make option FPC="/path/to/your/3.2.2/fpc/executable" with additional/required build options.
- Place/copy/move your freshly copies of the FPC host and cross compiler somewhere that you want them to be located.
- Make a link, use an alias, or a script that invokes your FPC executable from the command line. Make sure to avoid placing the Free Pascal binary directory in your path (it clashes when you want to install multiple different versions of FPC on the same host).
- configure the compiler by editing your fpc.cfg file. In case there are multiple different version of Free Pascal that you want to use, as an advise make sure to only use one fpc.cfg file (f.e. you can use the -n override in combination with the (undocumented) @ symbol to point to another fpc..cfg file (with location)).
- determine which Lazarus version you wish to build, for example 2.2.4
- download and extract Lazarus sources, f.e. "
https://sourceforge.net/projects/lazarus/files/Lazarus%20Zip%20_%20GZip/Lazarus%202.2.4/lazarus-2.2.4-0.tar.gz"
- Build and install Lazarus using the freshly 3.2.2. compiler (make bigide PP="/path/to/your/fpc/3.2.2/executable/or/script/link/that/invokes/fpc").
- Make sure to invoke Lazarus with the option --pcp. f.e. use a desktop shortcut that reads something like "/home/username/lazarus/2.2.4/startlazarus --pcp=/home/username/lazarus/2.2.4/.lazconfig %f"
- On first run Lazarus will present a dialog and you need to answer a few questions about your setup/configuration, see also
https://forum.lazarus.freepascal.org/index.php?topic=61185.0 . Make sure that thre are no red exclamation marks left and if all locations are corresponding to your setup.
How to install lnet was outlined one of the previous posts. Basically the above is what I did to install lnet (I just done what is written in this post on an earlier occasion)