Resolved After Upgrade from Ubuntu 16.04 to 18.04, can't start apache due to syntax error in apache2.conf

[jradzuweit]

Hi,
I have done a dist-upgrade from 16.04 to 18.04 according to the KB articel but now I stuck with the following error message

root@vega:/etc/apache2# apachectl -t
apache2: Syntax error on line 140 of /etc/apache2/apache2.conf: Syntax error on line 2 of /etc/apache2/mods-enabled/proxy_wstunnel.load: Cannot load /usr/lib/apache2/modules/mod_proxy_wstunnel.so into server: /usr/lib/apache2/modules/mod_proxy_wstunnel.so: undefined symbol: ap_proxy_transfer_between_connections
Action '-t' failed.
The Apache error log may have more information.

The apache log has no more information and the mail contains the same as above.

Here some more details of the config files

root@vega:/etc/apache2# grep IncludeOptional -n apache2.conf
140:IncludeOptional mods-enabled/*.load
141:IncludeOptional mods-enabled/*.conf
216:IncludeOptional conf-enabled/*.conf
219:IncludeOptional sites-enabled/*.conf
root@vega:/etc/apache2# ls /etc/apache2/mods-enabled/proxy_wstunnel.load
/etc/apache2/mods-enabled/proxy_wstunnel.load
root@vega:/etc/apache2# cat /etc/apache2/mods-enabled/proxy_wstunnel.load
# Depends: proxy
LoadModule proxy_wstunnel_module /usr/lib/apache2/modules/mod_proxy_wstunnel.so
root@vega:/etc/apache2# ls -l /usr/lib/apache2/modules/mod_proxy_wstunnel.so
-rw-r--r-- 1 root root 18400 Aug 12 2020 /usr/lib/apache2/modules/mod_proxy_wstunnel.so
root@vega:/etc/apache2#

Maybe some wrong version of the shared lib?
Has anybody an idea how to fix this?

 

[Nik G]

hello @jradzuweit ,
as I remember there was a step in the instruction that you should disable apache proxy module.
did you try this?

 

[jradzuweit]

Yes, I have disabled the proxy module before. In the mean time I ran the

plesk repair web

disabled the module, the tool fixed the remaining errors and generaterd the apache config files new. Now everything works again.