One of the issues I came across again and again was the e.g., the Google Search Console error with “Text too small to read” and/or “Clickable elements too close together“.
This might hit you all of a sudden and can have multiple reasons.
The best way to start is using the F12 key in your browser and looking at the indicated page emulating a mobile device using the Toggle Device Emulation function. See if you can visually identify the issue right away. If not, it becomes trickier.
You can engage the Google Mobile-Friendly Test page and/or the Bing – Mobile Friendliness Test Tool to see if you can find out more. But as a matter of fact, they might not even find anything. Still, validating the fix, what will take days, might fail especially if you didn’t change anything.
You will quickly discover that there is a lot of talk about the html header tag “<meta name=”viewport” content=”width=device-width, initial-scale=1″>“, of course if you do not have this one yet, implement it, but if you use a current CMS like WordPress it is likely already there.
In my case it came down to the TAG CLOUD that showed a lot of TAGS and because of the sheer amount some of them became rather small und therefor closer together when it comes to clickable items. This seemed to be no issue visually but still, Google interpreted it as one.
Needless to say, that ignoring any errors thrown by the Google Search Console might cost you valuable ranking or simply cause Google to not index certain pages. Especially since Google is primarily focusing on mobile usability.