René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"font family ['serif'] not found. Falling back to DejaVu Sans","articleBody":"### Bug report\r\n\r\n**Bug summary**\r\n\r\nI'm intermittently getting the warning `font family ['serif'] not found. Falling back to DejaVu Sans` when plotting with `rc('text', usetex=True)` enabled. If I delete `~\\.cache\\matplotlib` the warning stops and the charts are rendered with the correct font. But a day or so later it starts again\r\n\r\n**Code for reproduction**\r\n\r\nCannot reliably reproduce as intermittent, can reliably fix by deleting `~\\.cache\\matplotlib`\r\n\r\n**Matplotlib version**\r\n\r\n  * Operating system: Ubuntu 18.04\r\n  * Matplotlib version: 3.0.2\r\n  * Matplotlib backend: module://ipykernel.pylab.backend_inline\r\n  * Python version: 3.7.1 x64\r\n  * Jupyter version (if applicable): 4.4.0\r\n  * Other libraries: \r\n\r\n\u003c!--Please tell us how you installed matplotlib and python e.g., from source, pip, conda--\u003e\r\n\u003c!--If you installed from conda, please specify which channel you used if not the default--\u003e\r\n\r\ninstalled from pip\r\n","author":{"url":"https://github.com/david-waterworth","@type":"Person","name":"david-waterworth"},"datePublished":"2019-01-09T22:22:42.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":58},"url":"https://github.com/13139/matplotlib/issues/13139"}