Showing Not Acceptable 406 error in laravel - laravel

Question

I am getting a new error and its first time I am facing such error. Whenever I submit form and if it contains '%' in any field, then it shows me the 406 Not Acceptable error.
Also, when I submit the form and any field didn't contain '%' then form is successfully submitted.
I have already tried adding
'charset' => 'utf8',
'collation' => 'utf8_unicode_ci',
in database.php but it didn't work.
Also, I have found in R&D that by adding 'mysql_real_escape_string' in PHP,, this can be resolved. But ho it can be used in laravel..
Please help me out,
Thanks in advance.
<div id="page-wrapper">
<div id="page-inner">
<div class="row">
<div class="col-md-12">
<div class="panel panel-default">
<div class="panel-body">
#include('admin.partials.flash_message')
<form action="{{ $action }}" method="post" enctype="multipart/form-data">
#csrf()
<?php /*#if(!empty($method)) #method($method) #endif*/ ?>
<div class="form-group">
<div class="row">
<div class="col-md-3">
<label>RFP Title <span class="text-danger">*</span> :</label>
</div>
<div class="col-md-9">
<input type="text" class="form-control" name="rfp_title" value="{{ $pageTitle }}" {{ $prop }} maxlength="100">
</div>
</div>
</div>
<div class="form-group">
<div class="row">
<div class="col-md-3">
<label>RFP Description <span class="text-danger">*</span> :</label>
</div>
<div class="col-md-9">
<textarea id="summernote" name="rfp_description"></textarea>
</div>
</div>
</div>
<div class="form-group">
<div class="row">
<div class="col-md-3">
<label>Organisation <span class="text-danger">*</span> :</label>
</div>
<div class="col-md-9">
<input type="text" class="form-control" name="organisation" value="{{ $pageTitle }}" {{ $prop }} maxlength="100">
</div>
</div>
</div>
<div class="form-group">
<div class="row">
<div class="col-md-3">
<label>Publish Date <span class="text-danger">*</span> :</label>
</div>
<div class="col-md-9">
<input type="text" class="form-control" name="publish_date" value="{{ $pageTitle }}" {{ $prop }} maxlength="100" readonly>
</div>
</div>
</div>
<div class="form-group">
<div class="row">
<div class="col-md-3">
<label>Closing Date <span class="text-danger">*</span> :</label>
</div>
<div class="col-md-9">
<input type="text" class="form-control" name="closing_date" value="{{ $pageTitle }}" {{ $prop }} maxlength="100" readonly>
</div>
</div>
</div>
<div class="form-group">
<div class="row">
<div class="col-md-3">
<label>Company Image <span class="text-danger">*</span> :</label>
</div>
<div class="col-md-9">
<input type="file" name="company_image" id="imageUpload" accept=".png,.jpg,.jpeg" class="hide">
<label for="imageUpload" class="upload-poster mr-5">Select file</label> Max Size 2 MB<br>
<img src="{{ asset('public/assets/admin/images/dummy-logo.jpg')}}" id="imagePreview" class="organisation-logo" alt="Your image will appear here.">
</div>
</div>
</div>
<div class="form-group">
<div class="row">
<div class="col-md-3">
<label>Attachment <span class="text-danger">*</span> :</label>
</div>
<div class="col-md-9">
<input type="file" name="attachment" id="file-2" class="inputfile" data-multiple-caption="{count} files selected" accept=".pdf,.doc,.docx" multiple>
<label for="file-2" class="mr-5"><svg xmlns="http://www.w3.org/2000/svg" width="20" height="17" viewBox="0 0 20 17"><path d="M10 0l-5.2 4.9h3.3v5.1h3.8v-5.1h3.3l-5.2-4.9zm9.3 11.5l-3.2-2.1h-2l3.4 2.6h-3.5c-.1 0-.2.1-.2.1l-.8 2.3h-6l-.8-2.2c-.1-.1-.1-.2-.2-.2h-3.6l3.4-2.6h-2l-3.2 2.1c-.4.3-.7 1-.6 1.5l.6 3.1c.1.5.7.9 1.2.9h16.3c.6 0 1.1-.4 1.3-.9l.6-3.1c.1-.5-.2-1.2-.7-1.5z"/></svg> <span>Select File</span></label> Max Size 2 MB
</div>
</div>
</div>
<div class="form-group">
<div class="row">
<div class="col-md-3">
<label>Contact Person :</label>
</div>
<div class="col-md-9">
<input type="text" class="form-control" name="contact_person" value="{{ $pageTitle }}" {{ $prop }} maxlength="100">
</div>
</div>
</div>
<div class="form-group" style="margin-top: 20px;">
<input type="submit" class="btn btn-primary" value="Submit" name="btn_btn_add_product" {{ $prop }}>
</div>
</form>
</div>
</div>
</div>
</div>
</div>
</div>