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docs/source/development/FAQ.md

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+# Frequently asked questions
+
+## Continuous integration
+
+Pipeline fails, but php-cs-fixer doesn't alert me when running it locally?
+========================================
+
+It is possible that you run php-cs-fixer on your local instance of chill and no fixes are made.
+Everything seems fine, so you push. However, once the pipeline is run in gitlab, you're notified that it failed due to php
+cs errors.
+
+In this case it's likely that you have to update your version of php-cs-fixer.
+php-cs-fixer is installed when building the docker image: https://gitea.champs-libres.be/Chill-project/chill-skeleton-basic/src/branch/main/Dockerfile#L50
+
+Consequently, to update php-cs-fixer, we have to update the image by building it again.
+
+For this the following commands can be used.
+
+```
+    docker compose build --pull php
+    # replace existing containers
+    docker compose up -d --force-recreate php
+```