This error message was introduced in version 2.12.4.
It appears if the syntax of conditional pausing rule is incorrect.
Resilio Connect Agent cannot verify if the rule itself is logically correct, but it can recognize some of the invalid syntax, for example, extra or missing symbols, unexpected operands, tags' case, etc.
The error message reports only the first discovered place with the broken syntax. Check the whole rule just in case, otherwise another error message may arise.
Example of a valid rule:
(TAG_1=ABC OR TAG_1=XYZ) AND NOT TAG_2 = MNO
Examples of invalid rules:
" NOT NOT(T1=V()1)"
Error code SE_SM_TAGS_CONDITION