Textarea limit of 6,020ish characters

[lukecarbis]

When putting more than 6,020 characters in a text box, the following error is displayed:

Error loading block: The response is not a valid JSON response.

[lukecarbis]

The max number of characters seems to vary. It's more likely that it's a filesize (kb) limit.

[lukecarbis]

Additionally, it seems like it's not actually the size of the textarea text that matters, but the size of the entire JSON once it's saved. For example, you could have a single textarea that fits a whole bunch of characters before it errors, or multiple textareas that fit much less text before it errors.

Lastly, its seems like non-english text (e.g. Cyrillic) may contribute to the problem.

[kienstra]

It looks like this support topic has a similar issue:

Yes, if add too much text in textarea field type it isn’t rendering in block editor

[kienstra]

Here's another related support topic:
https://wordpress.org/support/topic/json-error-20/

[cgodefroy]

You might check your other plugins: Popup Maker is a likely culprit. At least, for me it is the event that created the issue. I've not investigated more.