When I would like to stop/restart Apache, Show the MESSAGE below, and cannot restart!
I cannot install the second SSL website also!The same error message!
Ask for HELP,Thanks.

Traceback (most recent call last):
File "class/public.py", line 601, in ExecShell
sub = subprocess.Popen(cmdstring, close_fds=True, shell=shell,bufsize=128,stdout=succ_f,stderr=err_f,cwd=cwd,env=env,preexec_fn=preexec_fn)
File "/www/server/panel/pyenv/lib/python3.7/site-packages/gevent/subprocess.py", line 816, in init
start_new_session)
File "/www/server/panel/pyenv/lib/python3.7/site-packages/gevent/subprocess.py", line 1603, in execute_child
self.pid = fork_and_watch(self.on_child, self._loop, True, fork)
File "/www/server/panel/pyenv/lib/python3.7/site-packages/gevent/os.py", line 431, in fork_and_watch
pid = fork()
BlockingIOError: [Errno 11] Resource temporarily unavailable

When I install the second SSL website, It also show the message, same with above "Apache rule configuration error"。

    Hello, is the website's certificate configured correctly? If the configuration is incorrect, apache will not be able to start, try to close ssl, and then restart is it normal?

    aaP_alfredlin015

        aaPanel_Kern
        I have installed the first website with SSL, it works fine. And then, I would like to install the second website SSL, show the error message as above.
        And the Apache can work, but cannot restart! Its error message shown as above.
        Compare these two messages, just header is different (one is "Apache rule configuration error:", another is "Certificate ERROR, please check!:"), but look into its content ~~~ all same! Check the last line: "BlockingIOError: [Errno 11] Resource temporarily unavailable", I don't understand it.

            aaPanel_Kern
            Thanks for reply. I have made the test that disabled site one SSL and enabled site two SSL and work fine! Only one SSL site work whether it is site one or site two! So I think the problem should be something resource that I do not understand made the problem. As the error message shown :"BlockingIOError:[Errno 11] Resource temporarily unavailable"!

                Hi, can you give us your aapanel information? The server makes a snapshot backup first, if possible, please send it to kern@aapanel.com.
                It is recommended to fill in the following
                Post link:
                SSH IP address, account password and port:
                aapanel login link address and account password:

                No post link will not be able to know which user's information is, and the problem will not be processed

                aaP_alfredlin015

                  2 years later

                  Fix: Apache Fails to Start with "mod_lua.so" Error in aaPanel
                  Error Description
                  When starting or restarting Apache in aaPanel, users may encounter the following error:

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                  httpd: Syntax error on line 502 of /www/server/apache/conf/httpd.conf:
                  Syntax error on line 1 of /www/server/panel/vhost/apache/btwaf.conf:
                  Cannot load modules/mod_lua.so into server: liblua5.3.so.0: cannot open shared object file: No such file or directory
                  This happens because Apache’s WAF (mod_lua) requires liblua5.3, but it’s missing on the system.

                  Solution (Verified Working)

                  1. Install liblua5.3 (Required Dependency)
                    Run the appropriate command for your OS:

                  For Debian/Ubuntu:
                  bash
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                  sudo apt-get update && sudo apt-get install liblua5.3-0 -y
                  For CentOS/RockyLinux/AlmaLinux:
                  bash
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                  sudo yum install lua5.3 -y
                  For Arch Linux (if applicable):
                  bash
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                  sudo pacman -S lua53

                  1. Restart Apache
                    After installing liblua5.3, restart Apache:

                  bash
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                  systemctl restart httpd # For Apache
                  ✅ Apache should now start without errors.

                  Alternative Fixes (If the Problem Persists)
                  A. Reinstall Apache with Lua Support
                  If the error remains, reinstall Apache via aaPanel:

                  bash
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                  cd /www/server/panel/install
                  ./install_soft.sh 0 apache 2.4
                  B. Disable mod_lua (Temporary Fix)
                  If you don’t need Lua support (e.g., not using WAF), disable it:

                  Edit the WAF config:

                  bash
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                  nano /www/server/panel/vhost/apache/btwaf.conf
                  Comment out this line:

                  apache
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                  LoadModule lua_module modules/mod_lua.so

                  Restart Apache:

                  bash
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                  systemctl restart httpd
                  C. Reinstall aaPanel’s WAF Module
                  If the issue is still unresolved, reinstall the WAF:

                  bash
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                  sh /www/server/panel/install/install_soft.sh 0 waf
                  Preventive Measures
                  Keep aaPanel Updated

                  bash
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                  bt update
                  Check Dependencies Before Installing Apache/Nginx

                  Ensure liblua5.3 is installed before enabling WAF.

                  Final Notes
                  This issue is common after fresh aaPanel installations or Apache updates.

                  If you still face problems, check logs:

                  bash
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                  tail -n 50 /www/server/apache/logs/error_log
                  💡 Did this solve your issue? Let others know in the replies! If you have a different solution, share it below.

                  Credits
                  Reported by: Kostas

                  Tested on: [Your OS, e.g., Ubuntu 22.04 / CentOS 7]

                  aaPanel Version: [Your aaPanel version, 2.5.0

                  Connect with us: 📨 Telegram 💬 Discord Email: support@aapanel.com