The system I have is running Raspbian Buster on an RPi4B with 4GB RAM. I use FPC 3.0.4 and Lazarus 2.0.4

Today I was going to transfer a project from Windows to Raspbian through Subversion and then I needed to install some dependencies into Lazarus too.
Specifically I used Online Package Manager from the Package menu to find and install UniqueInstance.

The process ran for a while then asked me if I wanted to rebuild Lazarus IDE, which I replied yes to and after a little while it stopped with a displayed message:
Build IDE: Exit code 2, Errors 1
Fatal: Unit IDECmdLine searched but LazConf found

At this point the IDE is still visible on screen but totally unresponsive, cannot even be closed and no menus respond to mouse clicks.

In a terminal I can see this:
pi at rpi4-gui:~ $ ps aux |grep lazarus
pi 31262 0.0 0.5 38492 23992 ? S 22:53 0:00 /home/pi/dev/lazarus/2.0.4/startlazarus --pcp=/home/pi/.lazarus_2.0.4 pi 31264 3.8 2.2 146760 89456 ? Sl 22:53 0:48 /home/pi/dev/lazarus/2.0.4/lazarus --no-splash-screen --started-by-startlazarus --pcp=/home/pi/.lazarus_2.0.4 --force-new-instance

What is the cause of this problem and what can I do to solve it?

Kill lazarus via terminal or what?

Bo Berglund wrote

At this point the IDE is still visible on screen but totally unresponsive, cannot even be closed and no menus respond to mouse clicks.

And it is repeatable too...
If I kill the lazarus process launched from Lazarus to rebuild itself both lazaus instances unload and the screen is empty. If I then start over by starting Lazarus and this time creating a new project to get away from my working code for the previous project the exact same thing happens when I try to install UniqueInstance from OnLine Package Manager.
Lazarus locks up.....

Why?

Note: I interact with the desktop on the RPi4 box via RealVNC.

Bo Berglund wrote

What is the cause of this problem and what can I do to solve it? Kill lazarus via terminal or what?

So this is what I did to get the system running:

- killed lazarus so it was not running in hanged state
- In a terminal I did:
pi at rpi4-gui:~/dev/lazarus/2.0.4 $ time make bigide OPT=-dFPC_ARMHF FPC=/home/pi/bin/ppcarm

After 6 minutes it was done and then I opened Lazarus and used OLPM to install the uniqueinstance package.

This time the rebuild of the Lazarus IDE succeeded and the package icon was installed into the System tab.

It seems like lazarus is now ready to be used.

So I opened the project I migrated from svn and tried to build it. Now I got this message:

Compile Project, Target: ssmonitorctrl: Success, Warnings: 12, Hints: 45
......
ssmonitorctrl.lpr(73,28) Warning: "crtbegin.o" not found, this will probably cause a linking failure
ssmonitorctrl.lpr(73,28) Warning: "crtend.o" not found, this will probably cause a linking failure

It seems like something needs to be done "somewhere" in order to fix this warning (I have not seen it in a long time), but where?

I don't really know why this all happened, but it might have something to do with me moving the complete fpc/lazarus installation from one SDcard to another with a fresh operating system installed.

I have installed FPC and Lazarus from sources downloaded via subversion and done this entirely in the user pi home directory. I spent some time on figuring out how to confine these tools entirely into the home dir so as not to depend on any stuff outside home except for the dependencies installed by apt.
All of the dependencies I know of were installed into the new operating system before I copied over the home dirs. And it seemed to work just fine until tye IDE rebuild.

Now I wonder if the lazarus "make bigide" puts or modifies stuff outside of the home dir, which I then have failed to copy in from the old installation? The make seems to have corrected whatever problöem was causing the crash...

And is there really something outside of home that fpc or lazarus depends on and is not part of the operating system???