title: Solr - How to fix "Error adding field ... msg=For input string" when post data to core
body: <p>I am new to Solr. 
  I created a Solr(8.1.0) core using SolrCloud for testing, and try to post data as a json file.</p>
  
  <p>When an object has a value with float like "spalte412": "35.5" or with special characters, it throws an error in the in the console:</p>
  
  <pre><code>SimplePostTool: WARNING: Response: {
    "responseHeader":{
      "rf":2,
      "status":400,
      "QTime":223},
    "error":{
      "metadata":[
        "error-class","org.apache.solr.common.SolrException",
        "root-error-class","java.lang.NumberFormatException"],
      "msg":"ERROR: [doc=52] Error adding field 'spalte421'='156.6' msg=For input string: \"156.6\"",
      "code":400}}
  </code></pre>
  
  <p>I tried to edit core Schema by adding the field, in the Admin UI, without success.</p>
  
  <p>Thanks for you help !</p>