Retrofit error URL query string must not have replace block

From the JavaDoc:

Example 1:

@GET("/friends")
 Call<ResponseBody> friends(@Query("page") int page);

Calling with foo.friends(1) yields /friends?page=1. Example with null:

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Example 2:

@GET("/friends")
 Call<ResponseBody> friends(@Query("group") String group);

Calling with foo.friends(null) yields /friends. Array/Varargs Example:

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Example 3:

@GET("/friends")
 Call<ResponseBody> friends(@Query("group") String... groups);

Calling with foo.friends("coworker", "bowling") yields /friends?group=coworker&group=bowling. Parameter names and values are URL encoded by default. Specify encoded=true to change this behavior.

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Example 4:

@GET("/friends")
 Call<ResponseBody> friends(@Query(value="group", encoded=true) String group);

Calling with foo.friends("foo+bar")) yields /friends?group=foo+bar.

 URL="/api-mobile_prateek2.php?method=getProductById&pid="


 @GET("/api-mobile_prateek2.php?method=getProductById")
    Call<Product> responseproduct(@Query("pid") String pid);

dont put the pid in the @GET,, Retrofit automatically fix the url, using @Query

Query params have their own annotation which automatically appends to the URL.

@GET("/users?filters[0][operator]=equals")
UserDto retrieveUsersByFilters(
    @Query("filters[0][field]") String nameFilter,
    @Query("filters[0][value]") String value);

You can read more about @Query on its Javadoc