Example 5 rows of my problematic data time series. Each one of the fields is a string (except date, blockNumber and removed) with a length of 42 chars, except for data, which can be anywhere from 32 to 2000 chars. I suspect this field as problematic and I will see if removing it solves the issue.

                                         address  blockNumber                                               data
7368  0x86fa049857e0209aa7d9e616f7eb3b3b78ecfdb0      4009999  0x00000000000000000000000000000000000000000000...
7369  0x86fa049857e0209aa7d9e616f7eb3b3b78ecfdb0      4009999  0x00000000000000000000000000000000000000000000...
7370  0x4470bb87d77b963a013db939be332f927f2b992e      4009999  0x00000000000000000000000000000000000000000000...
7371  0x888666ca69e0f178ded6d75b5726cee99a87d698      4009999  0x00000000000000000000000000000000000000000000...
7372  0x1a95b271b0535d15fa49932daba31ba612b52946      4009999  0x00000000000000000000000000000000000000000000...
            date
2017-07-12 01:26:36
2017-07-12 01:26:36
2017-07-12 01:26:36
2017-07-12 01:26:36
2017-07-12 01:26:36

                                             hash  removed                                            topic0
0xf6ff5a2784d6646fbebf884d68b48897f573d858f29d...    False  0xa9059cbb000000000000000000000000000000000000...
0xf6ff5a2784d6646fbebf884d68b48897f573d858f29d...    False  0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4...
0x305b8d17ed385e13203ac5f6c536710ef1ae8eca12bb...    False  0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4...
0x2acbd11a6f6f90e01a0f5e596fae3d7998fb845a93bc...    False  0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4...
0x4cd1773cb40984cbf6b19bf0e4df803f3185189495f6...    False  0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4...

                                          topic1
0x000000000000000000000000174443351e21d47ed9ab...
0x000000000000000000000000174443351e21d47ed9ab...
0x000000000000000000000000e8f3d4c67c504f2cfdf5...
0x000000000000000000000000d3737fa55d3070d0e64c...
0x000000000000000000000000895924eb32d2f17c4d76...

                                            topic2                                             topic3
0x0000000000000000000000007a1d50a19aab8b6887d0...  0x00000000000000000000000000000000000000000000...
0x0000000000000000000000007a1d50a19aab8b6887d0...                                                NaN
0x00000000000000000000000071c2a6b9f5c036244642...                                                NaN
0x00000000000000000000000021b74a8f083bec850af8...                                                NaN
0x000000000000000000000000f0750ca9e73b8ba71e09...                                                NaN