Tshark "-Tfields" option not working

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As the error message indicates, there is no data.txt field. I think the field you're looking for is data.text.

You can check/verify which fields are valid for which version of Wireshark you're using by referencing the online Display Filter Reference page. For example, the valid data fields are currently listed as:

Field name  Description     Type    Versions
data.data   Data    Sequence of bytes   1.0.0 to 2.6.3
data.len    Length  Signed integer, 4 bytes     1.2.0 to 2.6.3
data.md5_hash   Payload MD5 hash    Character string    1.6.0 to 2.6.3
data.text   Text    Character string    1.4.0 to 2.6.3
data.uncompressed.data  Uncompressed Data   Sequence of bytes   2.6.0 to 2.6.3
data.uncompressed.len   Uncompressed Length     Signed integer, 4 bytes     2.6.0 to 2.6.3