Fixing deprecated code, relatedTo issue Working on fixing a lot of deprecated code, enviroment is setup as dev so getting a lot of warnings. Some are easily idetified, others are pretty generic and come from core files. Doesn't show where the issue is... So I have been going through each block template removing code till the page loads to narrow it down.

Example Warning:
strtolower() expects parameter 1 to be string, array given from /vendor/craftcms/cms/src/helpers/Db.php

 $firstVal = strtolower(reset($value));


I have narrowed an existing issue down to the following code from a block template, however I have tried a few different ways but the page will not load with the following code. Anyone know a way to resolve this, it seems to be an issue with the relatedTo

Source of problem? Setting up section

{% for feed in block.feeds %}
    {% if feed == 'all' %}
        {% set data = ['blog', 'caseStudies', 'dataSheets', 'events', 'news', 'webinars', 'whitePapers', 'artices', 'productDemos'] %}
        {% set break = true %}
    {% else %}
        {% set data = data|merge({ (loop.index0):feed }) %}
    {% endif %}
{% endfor %}


Source of problem? Setting up relatedTo

{% for related in block.relatedTo %}
    {% if related == 'All' %}
        {% set reldata = false %}
        {% set break = true %}
    {% else %}
        {% set reldata = reldata|merge({ (loop.index0):related }) %}
    {% endif %}
{% endfor %}


Then Setting up the query seems to be an issue with the section(data) but not sure what needs changed as I do not see a clear deprecation warning, or stacktrace

{% if reldata %}
    {% set tag = craft.tags.title(reldata) %}
    {% set feat = craft.entries.section(data).relatedTo(tag).limit(8).all() %}
{% else %}
    {% set feat = craft.entries.section(data).limit(8).all() %}
{% endif %}
This seems to have fixed the issue.

{% if reldata %}
    {% set tag = craft.tags.title(reldata|join(', ')) %}
    {% set feat = craft.entries.section(data|join(', ')).relatedTo(tag).limit(8).all() %}
{% else %}
    {% set feat = craft.entries.section(data|join(', ')).limit(8).all() %}
{% endif %}