When using the new option to force Shareplex to read from an old archive log and onwards during activation, one runs into the following error:
sp_ctrl> activate config <name> seqno=<value>; Sequence number must be a positive number
There is a typo in the command.
By mistake one used a semicolon at the end of the command (similar to commands terminated in SQL*Plus). As a result Shareplex failed to recognize the value of the archive log sequence # which Capture needed to process. After the semicolon is removed, the command will work fine and the activation will finish successfully barring any other problems.