[htaccess/server conf] edit forbidden after install

maybe try to disable some plugin and test step by step

Thanks for your suggestion, Micker, I guess you mean disable a Joomla or Flexicontent plug-in ? Where can I start ? Because, except JCE I have nothing else installed and the 403 error happened right from the beginning, immediately after installing Joomla, even before adding the french translation of Flexicontent.
I'll call the provider tomorrow to see if they have a helpful remark, maybe something is inherited from the main domain, that could be modified through the htaccess ? I have no idea, but I'll keep you posted !
I do hope something can be done, it's frustrating to be stopped right from the start ! Thanks anyway for your kind answer,
Best,
Corinne

hello
1 disable SEF
2 disable cache (all cache and check cache plugin)
3 did you try online or in local computer ?
4 try why basic template at first

1 disable SEF : I did !
2 disable cache (all cache and check cache plugin) : I disabled the cache plugin but couldn't find anything called check cache.
3 did you try online or in local computer ? I'm just starting online ! Everything went perfectly well on my local server, Flexicontent is doing a great job !
4 try why basic template at first : of course, but for the moment I can't even edit a category... Nothing changed, alas...

Hello,

i look at it ,

-- the problem is not related to FLEXIcontent,

-- the problem is present in all pages of your site backend or frontend,
and it is because of your WEB server (apache) configuration,
-- ALL URLs with an array variable will fail with this error

do this simple test

-- add to your page &aaa=1
it works
-- add to your page &aaa[]=1
you get an internal server error

Also a quick fix/test you could try is to try to delete/backup .htaccess in joomla folder and replace it with the joomla's default htaccess (i suggest this just in case it was altered)

-- The exact details of any "internal server error" can be found at the apache logs, (either check cpanel error log or (if this is empty) ask your webhost to tell you what is happening
(also tell them that if you add an array variable in your site urls then the apache is giving an internal server error)

Regards

Hello,
You are very right, the problem has nothing to do with Flexicontent, which works beautifully, still I hoped posting a message here would help me understand what was going wrong. That's what you did !
I checked my htaccess, it was incomplete, so I got the Joomla default one back and added my own stuff, and... bingo !
I obviously still have a lot to learn and I thank you for your kindness and patient advice ! I will for sure write a review, but more than that, is there any way to make a donation in gratitude for the time, skill, and attention offered ?
Corinne